diff --git a/example.c b/example.c
index b3038efb0..3465fbb37 100644
--- a/example.c
+++ b/example.c
@@ -3,7 +3,7 @@
 
 /* example.c - an example of using libpng
  *
- * Maintained 2018 Cosmin Truta
+ * Maintained 2018-2024 Cosmin Truta
  * Maintained 1998-2016 Glenn Randers-Pehrson
  * Maintained 1996-1997 Andreas Dilger
  * Written 1995-1996 Guy Eric Schalnat, Group 42, Inc.
@@ -259,9 +259,9 @@ int check_if_png(char *file_name, FILE **fp)
       return 0;
 
    /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature.
-    * Return nonzero (true) if they match.
+    * Return true if they match.
     */
-   return(!png_sig_cmp(buf, 0, PNG_BYTES_TO_CHECK));
+   return png_sig_cmp(buf, 0, PNG_BYTES_TO_CHECK) == 0;
 }
 
 /* Read a PNG file.  You may want to return an error code if the read
@@ -281,7 +281,7 @@ void read_png(char *file_name) /* We need to open the file */
    FILE *fp;
 
    if ((fp = fopen(file_name, "rb")) == NULL)
-      return (ERROR);
+      return ERROR;
 
 #else no_open_file /* prototype 2 */
 void read_png(FILE *fp, int sig_read) /* File is already open */
@@ -304,7 +304,7 @@ void read_png(FILE *fp, int sig_read) /* File is already open */
    if (png_ptr == NULL)
    {
       fclose(fp);
-      return (ERROR);
+      return ERROR;
    }
 
    /* Allocate/initialize the memory for image information.  REQUIRED. */
@@ -313,7 +313,7 @@ void read_png(FILE *fp, int sig_read) /* File is already open */
    {
       fclose(fp);
       png_destroy_read_struct(&png_ptr, NULL, NULL);
-      return (ERROR);
+      return ERROR;
    }
 
    /* Set error handling if you are using the setjmp/longjmp method (this is
@@ -326,7 +326,7 @@ void read_png(FILE *fp, int sig_read) /* File is already open */
       png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
       fclose(fp);
       /* If we get here, we had a problem reading the file. */
-      return (ERROR);
+      return ERROR;
    }
 
    /* One of the following I/O initialization methods is REQUIRED. */
@@ -585,7 +585,7 @@ void read_png(FILE *fp, int sig_read) /* File is already open */
    fclose(fp);
 
    /* That's it! */
-   return (OK);
+   return OK;
 }
 
 /* Progressively read a file */
@@ -604,18 +604,18 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
    if (*png_ptr == NULL)
    {
       *info_ptr = NULL;
-      return (ERROR);
+      return ERROR;
    }
    *info_ptr = png_create_info_struct(png_ptr);
    if (*info_ptr == NULL)
    {
       png_destroy_read_struct(png_ptr, info_ptr, NULL);
-      return (ERROR);
+      return ERROR;
    }
    if (setjmp(png_jmpbuf((*png_ptr))))
    {
       png_destroy_read_struct(png_ptr, info_ptr, NULL);
-      return (ERROR);
+      return ERROR;
    }
 
    /* You will need to provide all three function callbacks,
@@ -632,7 +632,7 @@ initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr)
     */
    png_set_progressive_read_fn(*png_ptr, (void *)stream_data,
        info_callback, row_callback, end_callback);
-   return (OK);
+   return OK;
 }
 
 int
@@ -643,7 +643,7 @@ process_data(png_structp *png_ptr, png_infop *info_ptr,
    {
       /* Free the png_ptr and info_ptr memory on error. */
       png_destroy_read_struct(png_ptr, info_ptr, NULL);
-      return (ERROR);
+      return ERROR;
    }
 
    /* Give chunks of data as they arrive from the data stream
@@ -657,7 +657,7 @@ process_data(png_structp *png_ptr, png_infop *info_ptr,
     * callback, if you aren't already displaying them there.
     */
    png_process_data(*png_ptr, *info_ptr, buffer, length);
-   return (OK);
+   return OK;
 }
 
 info_callback(png_structp png_ptr, png_infop info)
@@ -747,7 +747,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    /* Open the file */
    fp = fopen(file_name, "wb");
    if (fp == NULL)
-      return (ERROR);
+      return ERROR;
 
    /* Create and initialize the png_struct with the desired error handler
     * functions.  If you want to use the default stderr and longjump method,
@@ -760,7 +760,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    if (png_ptr == NULL)
    {
       fclose(fp);
-      return (ERROR);
+      return ERROR;
    }
 
    /* Allocate/initialize the image information data.  REQUIRED. */
@@ -769,7 +769,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    {
       fclose(fp);
       png_destroy_write_struct(&png_ptr,  NULL);
-      return (ERROR);
+      return ERROR;
    }
 
    /* Set up error handling.  REQUIRED if you aren't supplying your own
@@ -780,7 +780,7 @@ void write_png(char *file_name /* , ... other image information ... */)
       /* If we get here, we had a problem writing the file. */
       fclose(fp);
       png_destroy_write_struct(&png_ptr, &info_ptr);
-      return (ERROR);
+      return ERROR;
    }
 
    /* One of the following I/O initialization functions is REQUIRED. */
@@ -1035,7 +1035,7 @@ void write_png(char *file_name /* , ... other image information ... */)
    fclose(fp);
 
    /* That's it! */
-   return (OK);
+   return OK;
 }
 
 #endif /* if 0 */
diff --git a/png.c b/png.c
index 9cc560e6c..4d3fb52e5 100644
--- a/png.c
+++ b/png.c
@@ -59,15 +59,15 @@ png_sig_cmp(png_const_bytep sig, size_t start, size_t num_to_check)
       num_to_check = 8;
 
    else if (num_to_check < 1)
-      return (-1);
+      return -1;
 
    if (start > 7)
-      return (-1);
+      return -1;
 
    if (start + num_to_check > 8)
       num_to_check = 8 - start;
 
-   return ((int)(memcmp(&sig[start], &png_signature[start], num_to_check)));
+   return memcmp(&sig[start], &png_signature[start], num_to_check);
 }
 
 #endif /* READ */
@@ -665,9 +665,9 @@ png_voidp PNGAPI
 png_get_io_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
-      return (NULL);
+      return NULL;
 
-   return (png_ptr->io_ptr);
+   return png_ptr->io_ptr;
 }
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
@@ -956,7 +956,7 @@ png_reset_zstream(png_structrp png_ptr)
       return Z_STREAM_ERROR;
 
    /* WARNING: this resets the window bits to the maximum! */
-   return (inflateReset(&png_ptr->zstream));
+   return inflateReset(&png_ptr->zstream);
 }
 #endif /* READ */
 
@@ -965,7 +965,7 @@ png_uint_32 PNGAPI
 png_access_version_number(void)
 {
    /* Version of *.c files used when building libpng */
-   return((png_uint_32)PNG_LIBPNG_VER);
+   return (png_uint_32)PNG_LIBPNG_VER;
 }
 
 #if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED)
diff --git a/png.h b/png.h
index 861e84b86..6c72d68bc 100644
--- a/png.h
+++ b/png.h
@@ -908,15 +908,15 @@ PNG_EXPORT(2, void, png_set_sig_bytes, (png_structrp png_ptr, int num_bytes));
 /* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
  * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
  * signature, and non-zero otherwise.  Having num_to_check == 0 or
- * start > 7 will always fail (ie return non-zero).
+ * start > 7 will always fail (i.e. return non-zero).
  */
 PNG_EXPORT(3, int, png_sig_cmp, (png_const_bytep sig, size_t start,
     size_t num_to_check));
 
 /* Simple signature checking function.  This is the same as calling
- * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
+ * png_check_sig(sig, n) := (png_sig_cmp(sig, 0, n) != 0).
  */
-#define png_check_sig(sig, n) !png_sig_cmp((sig), 0, (n))
+#define png_check_sig(sig, n) (png_sig_cmp((sig), 0, (n)) != 0)
 
 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
 PNG_EXPORTA(4, png_structp, png_create_read_struct,
diff --git a/pngerror.c b/pngerror.c
index 3469959a6..29ebda794 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,7 +1,7 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Copyright (c) 2018 Cosmin Truta
+ * Copyright (c) 2018-2024 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
  * Copyright (c) 1996-1997 Andreas Dilger
  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
@@ -858,7 +858,7 @@ png_get_error_ptr(png_const_structrp png_ptr)
    if (png_ptr == NULL)
       return NULL;
 
-   return ((png_voidp)png_ptr->error_ptr);
+   return (png_voidp)png_ptr->error_ptr;
 }
 
 
diff --git a/pngget.c b/pngget.c
index 741a5be90..1084b268f 100644
--- a/pngget.c
+++ b/pngget.c
@@ -28,22 +28,22 @@ png_get_valid(png_const_structrp png_ptr, png_const_inforp info_ptr,
        * valid tRNS chunk in this case.
        */
       if (flag == PNG_INFO_tRNS && png_ptr->num_trans == 0)
-         return(0);
+         return 0;
 #endif
 
-      return(info_ptr->valid & flag);
+      return info_ptr->valid & flag;
    }
 
-   return(0);
+   return 0;
 }
 
 size_t PNGAPI
 png_get_rowbytes(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
-      return(info_ptr->rowbytes);
+      return info_ptr->rowbytes;
 
-   return(0);
+   return 0;
 }
 
 #ifdef PNG_INFO_IMAGE_SUPPORTED
@@ -51,9 +51,9 @@ png_bytepp PNGAPI
 png_get_rows(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
-      return(info_ptr->row_pointers);
+      return info_ptr->row_pointers;
 
-   return(0);
+   return 0;
 }
 #endif
 
@@ -65,7 +65,7 @@ png_get_image_width(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->width;
 
-   return (0);
+   return 0;
 }
 
 png_uint_32 PNGAPI
@@ -74,7 +74,7 @@ png_get_image_height(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->height;
 
-   return (0);
+   return 0;
 }
 
 png_byte PNGAPI
@@ -83,7 +83,7 @@ png_get_bit_depth(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->bit_depth;
 
-   return (0);
+   return 0;
 }
 
 png_byte PNGAPI
@@ -92,7 +92,7 @@ png_get_color_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->color_type;
 
-   return (0);
+   return 0;
 }
 
 png_byte PNGAPI
@@ -101,7 +101,7 @@ png_get_filter_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->filter_type;
 
-   return (0);
+   return 0;
 }
 
 png_byte PNGAPI
@@ -110,7 +110,7 @@ png_get_interlace_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->interlace_type;
 
-   return (0);
+   return 0;
 }
 
 png_byte PNGAPI
@@ -119,7 +119,7 @@ png_get_compression_type(png_const_structrp png_ptr, png_const_inforp info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return info_ptr->compression_type;
 
-   return (0);
+   return 0;
 }
 
 png_uint_32 PNGAPI
@@ -133,14 +133,14 @@ png_get_x_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp
        (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER)
-         return (info_ptr->x_pixels_per_unit);
+         return info_ptr->x_pixels_per_unit;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 png_uint_32 PNGAPI
@@ -154,14 +154,14 @@ png_get_y_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp
        (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER)
-         return (info_ptr->y_pixels_per_unit);
+         return info_ptr->y_pixels_per_unit;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 png_uint_32 PNGAPI
@@ -175,14 +175,14 @@ png_get_pixels_per_meter(png_const_structrp png_ptr, png_const_inforp info_ptr)
    {
       if (info_ptr->phys_unit_type == PNG_RESOLUTION_METER &&
           info_ptr->x_pixels_per_unit == info_ptr->y_pixels_per_unit)
-         return (info_ptr->x_pixels_per_unit);
+         return info_ptr->x_pixels_per_unit;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 #ifdef PNG_FLOATING_POINT_SUPPORTED
@@ -197,15 +197,15 @@ png_get_pixel_aspect_ratio(png_const_structrp png_ptr, png_const_inforp
        (info_ptr->valid & PNG_INFO_pHYs) != 0)
    {
       if (info_ptr->x_pixels_per_unit != 0)
-         return ((float)((float)info_ptr->y_pixels_per_unit
-             /(float)info_ptr->x_pixels_per_unit));
+         return (float)info_ptr->y_pixels_per_unit
+              / (float)info_ptr->x_pixels_per_unit;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return ((float)0.0);
+   return (float)0.0;
 }
 #endif
 
@@ -251,14 +251,14 @@ png_get_x_offset_microns(png_const_structrp png_ptr, png_const_inforp info_ptr)
        (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       if (info_ptr->offset_unit_type == PNG_OFFSET_MICROMETER)
-         return (info_ptr->x_offset);
+         return info_ptr->x_offset;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 png_int_32 PNGAPI
@@ -271,14 +271,14 @@ png_get_y_offset_microns(png_const_structrp png_ptr, png_const_inforp info_ptr)
        (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       if (info_ptr->offset_unit_type == PNG_OFFSET_MICROMETER)
-         return (info_ptr->y_offset);
+         return info_ptr->y_offset;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 png_int_32 PNGAPI
@@ -291,14 +291,14 @@ png_get_x_offset_pixels(png_const_structrp png_ptr, png_const_inforp info_ptr)
        (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       if (info_ptr->offset_unit_type == PNG_OFFSET_PIXEL)
-         return (info_ptr->x_offset);
+         return info_ptr->x_offset;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 png_int_32 PNGAPI
@@ -311,14 +311,14 @@ png_get_y_offset_pixels(png_const_structrp png_ptr, png_const_inforp info_ptr)
        (info_ptr->valid & PNG_INFO_oFFs) != 0)
    {
       if (info_ptr->offset_unit_type == PNG_OFFSET_PIXEL)
-         return (info_ptr->y_offset);
+         return info_ptr->y_offset;
    }
 #else
    PNG_UNUSED(png_ptr)
    PNG_UNUSED(info_ptr)
 #endif
 
-   return (0);
+   return 0;
 }
 
 #ifdef PNG_INCH_CONVERSIONS_SUPPORTED
@@ -462,7 +462,7 @@ png_get_pHYs_dpi(png_const_structrp png_ptr, png_const_inforp info_ptr,
       }
    }
 
-   return (retval);
+   return retval;
 }
 #endif /* pHYs */
 #endif /* INCH_CONVERSIONS */
@@ -476,9 +476,9 @@ png_byte PNGAPI
 png_get_channels(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
-      return(info_ptr->channels);
+      return info_ptr->channels;
 
-   return (0);
+   return 0;
 }
 
 #ifdef PNG_READ_SUPPORTED
@@ -486,9 +486,9 @@ png_const_bytep PNGAPI
 png_get_signature(png_const_structrp png_ptr, png_const_inforp info_ptr)
 {
    if (png_ptr != NULL && info_ptr != NULL)
-      return(info_ptr->signature);
+      return info_ptr->signature;
 
-   return (NULL);
+   return NULL;
 }
 #endif
 
@@ -504,10 +504,10 @@ png_get_bKGD(png_const_structrp png_ptr, png_inforp info_ptr,
        background != NULL)
    {
       *background = &(info_ptr->background);
-      return (PNG_INFO_bKGD);
+      return PNG_INFO_bKGD;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -557,10 +557,10 @@ png_get_cHRM(png_const_structrp png_ptr, png_const_inforp info_ptr,
       if (blue_y != NULL)
          *blue_y = png_float(png_ptr, info_ptr->colorspace.end_points_xy.bluey,
              "cHRM blue Y");
-      return (PNG_INFO_cHRM);
+      return PNG_INFO_cHRM;
    }
 
-   return (0);
+   return 0;
 }
 
 png_uint_32 PNGAPI
@@ -601,10 +601,10 @@ png_get_cHRM_XYZ(png_const_structrp png_ptr, png_const_inforp info_ptr,
       if (blue_Z != NULL)
          *blue_Z = png_float(png_ptr,
              info_ptr->colorspace.end_points_XYZ.blue_Z, "cHRM blue Z");
-      return (PNG_INFO_cHRM);
+      return PNG_INFO_cHRM;
    }
 
-   return (0);
+   return 0;
 }
 #  endif
 
@@ -640,10 +640,10 @@ png_get_cHRM_XYZ_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
          *int_blue_Y = info_ptr->colorspace.end_points_XYZ.blue_Y;
       if (int_blue_Z != NULL)
          *int_blue_Z = info_ptr->colorspace.end_points_XYZ.blue_Z;
-      return (PNG_INFO_cHRM);
+      return PNG_INFO_cHRM;
    }
 
-   return (0);
+   return 0;
 }
 
 png_uint_32 PNGAPI
@@ -673,10 +673,10 @@ png_get_cHRM_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
          *blue_x = info_ptr->colorspace.end_points_xy.bluex;
       if (blue_y != NULL)
          *blue_y = info_ptr->colorspace.end_points_xy.bluey;
-      return (PNG_INFO_cHRM);
+      return PNG_INFO_cHRM;
    }
 
-   return (0);
+   return 0;
 }
 #  endif
 #endif
@@ -694,10 +694,10 @@ png_get_gAMA_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
        file_gamma != NULL)
    {
       *file_gamma = info_ptr->colorspace.gamma;
-      return (PNG_INFO_gAMA);
+      return PNG_INFO_gAMA;
    }
 
-   return (0);
+   return 0;
 }
 #  endif
 
@@ -714,10 +714,10 @@ png_get_gAMA(png_const_structrp png_ptr, png_const_inforp info_ptr,
    {
       *file_gamma = png_float(png_ptr, info_ptr->colorspace.gamma,
           "png_get_gAMA");
-      return (PNG_INFO_gAMA);
+      return PNG_INFO_gAMA;
    }
 
-   return (0);
+   return 0;
 }
 #  endif
 #endif
@@ -733,10 +733,10 @@ png_get_sRGB(png_const_structrp png_ptr, png_const_inforp info_ptr,
       (info_ptr->valid & PNG_INFO_sRGB) != 0 && file_srgb_intent != NULL)
    {
       *file_srgb_intent = info_ptr->colorspace.rendering_intent;
-      return (PNG_INFO_sRGB);
+      return PNG_INFO_sRGB;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -760,10 +760,10 @@ png_get_iCCP(png_const_structrp png_ptr, png_inforp info_ptr,
        */
       if (compression_type != NULL)
          *compression_type = PNG_COMPRESSION_TYPE_BASE;
-      return (PNG_INFO_iCCP);
+      return PNG_INFO_iCCP;
    }
 
-   return (0);
+   return 0;
 
 }
 #endif
@@ -781,7 +781,7 @@ png_get_sPLT(png_const_structrp png_ptr, png_inforp info_ptr,
       return info_ptr->splt_palettes_num;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -807,10 +807,10 @@ png_get_eXIf_1(png_const_structrp png_ptr, png_const_inforp info_ptr,
    {
       *num_exif = info_ptr->num_exif;
       *exif = info_ptr->exif;
-      return (PNG_INFO_eXIf);
+      return PNG_INFO_eXIf;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -825,10 +825,10 @@ png_get_hIST(png_const_structrp png_ptr, png_inforp info_ptr,
        (info_ptr->valid & PNG_INFO_hIST) != 0 && hist != NULL)
    {
       *hist = info_ptr->hist;
-      return (PNG_INFO_hIST);
+      return PNG_INFO_hIST;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -841,7 +841,7 @@ png_get_IHDR(png_const_structrp png_ptr, png_const_inforp info_ptr,
    png_debug1(1, "in %s retrieval function", "IHDR");
 
    if (png_ptr == NULL || info_ptr == NULL)
-      return (0);
+      return 0;
 
    if (width != NULL)
        *width = info_ptr->width;
@@ -873,7 +873,7 @@ png_get_IHDR(png_const_structrp png_ptr, png_const_inforp info_ptr,
        info_ptr->bit_depth, info_ptr->color_type, info_ptr->interlace_type,
        info_ptr->compression_type, info_ptr->filter_type);
 
-   return (1);
+   return 1;
 }
 
 #ifdef PNG_oFFs_SUPPORTED
@@ -890,10 +890,10 @@ png_get_oFFs(png_const_structrp png_ptr, png_const_inforp info_ptr,
       *offset_x = info_ptr->x_offset;
       *offset_y = info_ptr->y_offset;
       *unit_type = (int)info_ptr->offset_unit_type;
-      return (PNG_INFO_oFFs);
+      return PNG_INFO_oFFs;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -917,10 +917,10 @@ png_get_pCAL(png_const_structrp png_ptr, png_inforp info_ptr,
       *nparams = (int)info_ptr->pcal_nparams;
       *units = info_ptr->pcal_units;
       *params = info_ptr->pcal_params;
-      return (PNG_INFO_pCAL);
+      return PNG_INFO_pCAL;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -945,10 +945,10 @@ png_get_sCAL_fixed(png_const_structrp png_ptr, png_const_inforp info_ptr,
       *width = png_fixed(png_ptr, atof(info_ptr->scal_s_width), "sCAL width");
       *height = png_fixed(png_ptr, atof(info_ptr->scal_s_height),
           "sCAL height");
-      return (PNG_INFO_sCAL);
+      return PNG_INFO_sCAL;
    }
 
-   return(0);
+   return 0;
 }
 #    endif /* FLOATING_ARITHMETIC */
 #  endif /* FIXED_POINT */
@@ -965,10 +965,10 @@ png_get_sCAL(png_const_structrp png_ptr, png_const_inforp info_ptr,
       *unit = info_ptr->scal_unit;
       *width = atof(info_ptr->scal_s_width);
       *height = atof(info_ptr->scal_s_height);
-      return (PNG_INFO_sCAL);
+      return PNG_INFO_sCAL;
    }
 
-   return(0);
+   return 0;
 }
 #  endif /* FLOATING POINT */
 png_uint_32 PNGAPI
@@ -983,10 +983,10 @@ png_get_sCAL_s(png_const_structrp png_ptr, png_const_inforp info_ptr,
       *unit = info_ptr->scal_unit;
       *width = info_ptr->scal_s_width;
       *height = info_ptr->scal_s_height;
-      return (PNG_INFO_sCAL);
+      return PNG_INFO_sCAL;
    }
 
-   return(0);
+   return 0;
 }
 #endif /* sCAL */
 
@@ -1021,7 +1021,7 @@ png_get_pHYs(png_const_structrp png_ptr, png_const_inforp info_ptr,
       }
    }
 
-   return (retval);
+   return retval;
 }
 #endif /* pHYs */
 
@@ -1037,10 +1037,10 @@ png_get_PLTE(png_const_structrp png_ptr, png_inforp info_ptr,
       *palette = info_ptr->palette;
       *num_palette = info_ptr->num_palette;
       png_debug1(3, "num_palette = %d", *num_palette);
-      return (PNG_INFO_PLTE);
+      return PNG_INFO_PLTE;
    }
 
-   return (0);
+   return 0;
 }
 
 #ifdef PNG_sBIT_SUPPORTED
@@ -1054,10 +1054,10 @@ png_get_sBIT(png_const_structrp png_ptr, png_inforp info_ptr,
        (info_ptr->valid & PNG_INFO_sBIT) != 0 && sig_bit != NULL)
    {
       *sig_bit = &(info_ptr->sig_bit);
-      return (PNG_INFO_sBIT);
+      return PNG_INFO_sBIT;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -1083,7 +1083,7 @@ png_get_text(png_const_structrp png_ptr, png_inforp info_ptr,
    if (num_text != NULL)
       *num_text = 0;
 
-   return(0);
+   return 0;
 }
 #endif
 
@@ -1098,10 +1098,10 @@ png_get_tIME(png_const_structrp png_ptr, png_inforp info_ptr,
        (info_ptr->valid & PNG_INFO_tIME) != 0 && mod_time != NULL)
    {
       *mod_time = &(info_ptr->mod_time);
-      return (PNG_INFO_tIME);
+      return PNG_INFO_tIME;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -1148,7 +1148,7 @@ png_get_tRNS(png_const_structrp png_ptr, png_inforp info_ptr,
       }
    }
 
-   return (retval);
+   return retval;
 }
 #endif
 
@@ -1163,7 +1163,7 @@ png_get_unknown_chunks(png_const_structrp png_ptr, png_inforp info_ptr,
       return info_ptr->unknown_chunks_num;
    }
 
-   return (0);
+   return 0;
 }
 #endif
 
@@ -1259,7 +1259,7 @@ png_get_palette_max(png_const_structp png_ptr, png_const_infop info_ptr)
    if (png_ptr != NULL && info_ptr != NULL)
       return png_ptr->num_palette_max;
 
-   return (-1);
+   return -1;
 }
 #  endif
 #endif
diff --git a/pngpread.c b/pngpread.c
index e283627b7..be640f77a 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -1,7 +1,7 @@
 
 /* pngpread.c - read a png file in push mode
  *
- * Copyright (c) 2018 Cosmin Truta
+ * Copyright (c) 2018-2024 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
  * Copyright (c) 1996-1997 Andreas Dilger
  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
@@ -145,10 +145,10 @@ png_push_read_sig(png_structrp png_ptr, png_inforp info_ptr)
        num_to_check);
    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);
 
-   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
+   if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
    {
       if (num_checked < 4 &&
-          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4) != 0)
          png_error(png_ptr, "Not a PNG file");
 
       else
@@ -1089,7 +1089,7 @@ png_voidp PNGAPI
 png_get_progressive_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
-      return (NULL);
+      return NULL;
 
    return png_ptr->io_ptr;
 }
diff --git a/pngrutil.c b/pngrutil.c
index b3e734bf6..d31dc21da 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -26,7 +26,7 @@ png_get_uint_31(png_const_structrp png_ptr, png_const_bytep buf)
    if (uval > PNG_UINT_31_MAX)
       png_error(png_ptr, "PNG unsigned integer out of range");
 
-   return (uval);
+   return uval;
 }
 
 #if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_READ_cHRM_SUPPORTED)
@@ -140,7 +140,7 @@ png_read_sig(png_structrp png_ptr, png_inforp info_ptr)
    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check) != 0)
    {
       if (num_checked < 4 &&
-          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
+          png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4) != 0)
          png_error(png_ptr, "Not a PNG file");
       else
          png_error(png_ptr, "PNG file corrupted by ASCII conversion");
@@ -238,10 +238,10 @@ png_crc_finish(png_structrp png_ptr, png_uint_32 skip)
       else
          png_chunk_error(png_ptr, "CRC error");
 
-      return (1);
+      return 1;
    }
 
-   return (0);
+   return 0;
 }
 
 /* Compare the CRC stored in the PNG file with that calculated by libpng from
@@ -277,11 +277,11 @@ png_crc_error(png_structrp png_ptr)
    if (need_crc != 0)
    {
       crc = png_get_uint_32(crc_bytes);
-      return ((int)(crc != png_ptr->crc));
+      return crc != png_ptr->crc;
    }
 
    else
-      return (0);
+      return 0;
 }
 
 #if defined(PNG_READ_iCCP_SUPPORTED) || defined(PNG_READ_iTXt_SUPPORTED) ||\
diff --git a/pngset.c b/pngset.c
index 2763d5da7..eb1c8c7a3 100644
--- a/pngset.c
+++ b/pngset.c
@@ -767,7 +767,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
       png_ptr == NULL ? 0xabadca11UL : (unsigned long)png_ptr->chunk_name);
 
    if (png_ptr == NULL || info_ptr == NULL || num_text <= 0 || text_ptr == NULL)
-      return(0);
+      return 0;
 
    /* Make sure we have enough space in the "text" array in info_struct
     * to hold all of the incoming text_ptr objects.  This compare can't overflow
@@ -947,7 +947,7 @@ png_set_text_2(png_const_structrp png_ptr, png_inforp info_ptr,
       png_debug1(3, "transferred text chunk %d", info_ptr->num_text);
    }
 
-   return(0);
+   return 0;
 }
 #endif
 
diff --git a/pngtest.c b/pngtest.c
index 865a3fb56..a078130b9 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -524,7 +524,7 @@ PNGCBAPI png_debug_malloc(png_structp png_ptr, png_alloc_size_t size)
     */
 
    if (size == 0)
-      return (NULL);
+      return NULL;
 
    /* This calls the library allocator twice, once to get the requested
       buffer and once to get a new free list entry. */
@@ -565,7 +565,7 @@ PNGCBAPI png_debug_malloc(png_structp png_ptr, png_alloc_size_t size)
          printf("png_malloc %lu bytes at %p\n", (unsigned long)size,
              pinfo->pointer);
 
-      return (png_voidp)(pinfo->pointer);
+      return (png_voidp)pinfo->pointer;
    }
 }
 
@@ -698,9 +698,9 @@ read_user_chunk_callback(png_struct *png_ptr, png_unknown_chunkp chunk)
       png_error(png_ptr, "lost user chunk pointer");
 
    /* Return one of the following:
-    *    return (-n);  chunk had an error
-    *    return (0);  did not recognize
-    *    return (n);  success
+    *    return -n;  chunk had an error
+    *    return 0;   did not recognize
+    *    return n;   success
     *
     * The unknown chunk structure contains the chunk data:
     * png_byte name[5];
@@ -715,38 +715,38 @@ read_user_chunk_callback(png_struct *png_ptr, png_unknown_chunkp chunk)
       {
          /* Found sTER chunk */
          if (chunk->size != 1)
-            return (-1); /* Error return */
+            return -1; /* Error return */
 
          if (chunk->data[0] != 0 && chunk->data[0] != 1)
-            return (-1);  /* Invalid mode */
+            return -1;  /* Invalid mode */
 
          if (set_location(png_ptr, my_user_chunk_data, have_sTER) != 0)
          {
             my_user_chunk_data->sTER_mode=chunk->data[0];
-            return (1);
+            return 1;
          }
 
          else
-            return (0); /* duplicate sTER - give it to libpng */
+            return 0; /* duplicate sTER - give it to libpng */
       }
 
    if (chunk->name[0] != 118 || chunk->name[1] != 112 ||    /* v  p */
        chunk->name[2] !=  65 || chunk->name[3] != 103)      /* A  g */
-      return (0); /* Did not recognize */
+      return 0; /* Did not recognize */
 
    /* Found ImageMagick vpAg chunk */
 
    if (chunk->size != 9)
-      return (-1); /* Error return */
+      return -1; /* Error return */
 
    if (set_location(png_ptr, my_user_chunk_data, have_vpAg) == 0)
-      return (0);  /* duplicate vpAg */
+      return 0;  /* duplicate vpAg */
 
    my_user_chunk_data->vpAg_width = png_get_uint_31(png_ptr, chunk->data);
    my_user_chunk_data->vpAg_height = png_get_uint_31(png_ptr, chunk->data + 4);
    my_user_chunk_data->vpAg_units = chunk->data[8];
 
-   return (1);
+   return 1;
 }
 
 #ifdef PNG_WRITE_SUPPORTED
@@ -882,14 +882,14 @@ test_one_file(const char *inname, const char *outname)
    if ((fpin = fopen(inname, "rb")) == NULL)
    {
       fprintf(STDERR, "Could not find input file %s\n", inname);
-      return (1);
+      return 1;
    }
 
    if ((fpout = fopen(outname, "wb")) == NULL)
    {
       fprintf(STDERR, "Could not open output file %s\n", outname);
       FCLOSE(fpin);
-      return (1);
+      return 1;
    }
 
    pngtest_debug("Allocating read and write structures");
@@ -948,7 +948,7 @@ test_one_file(const char *inname, const char *outname)
 #endif
       FCLOSE(fpin);
       FCLOSE(fpout);
-      return (1);
+      return 1;
    }
 
 #ifdef PNG_WRITE_SUPPORTED
@@ -968,7 +968,7 @@ test_one_file(const char *inname, const char *outname)
       png_destroy_write_struct(&write_ptr, &write_info_ptr);
       FCLOSE(fpin);
       FCLOSE(fpout);
-      return (1);
+      return 1;
    }
 #endif
 #endif
@@ -1686,7 +1686,7 @@ test_one_file(const char *inname, const char *outname)
           inname, error_count, warning_count);
 
       if (strict != 0)
-         return (1);
+         return 1;
    }
 
 #  ifdef PNG_WRITE_SUPPORTED
@@ -1704,21 +1704,21 @@ test_one_file(const char *inname, const char *outname)
           inname, warning_count);
 
       if (strict != 0)
-         return (1);
+         return 1;
    }
 
    pngtest_debug("Opening files for comparison");
    if ((fpin = fopen(inname, "rb")) == NULL)
    {
       fprintf(STDERR, "Could not find file %s\n", inname);
-      return (1);
+      return 1;
    }
 
    if ((fpout = fopen(outname, "rb")) == NULL)
    {
       fprintf(STDERR, "Could not find file %s\n", outname);
       FCLOSE(fpin);
-      return (1);
+      return 1;
    }
 
 #if defined (PNG_WRITE_SUPPORTED) /* else nothing was written */ &&\
@@ -1757,10 +1757,10 @@ test_one_file(const char *inname, const char *outname)
             FCLOSE(fpout);
 
             if (strict != 0 && unsupported_chunks == 0)
-              return (1);
+              return 1;
 
             else
-              return (0);
+              return 0;
          }
 
          if (num_in == 0)
@@ -1794,10 +1794,10 @@ test_one_file(const char *inname, const char *outname)
              * can be exactly the same size!
              */
             if (strict != 0 && unsupported_chunks == 0)
-              return (1);
+              return 1;
 
             else
-              return (0);
+              return 0;
          }
       }
    }
@@ -1806,7 +1806,7 @@ test_one_file(const char *inname, const char *outname)
    FCLOSE(fpin);
    FCLOSE(fpout);
 
-   return (0);
+   return 0;
 }
 
 /* Input and output filenames */
diff --git a/pngtrans.c b/pngtrans.c
index 753a14a77..62cb21edf 100644
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -103,10 +103,10 @@ png_set_interlace_handling(png_structrp png_ptr)
    if (png_ptr != 0 && png_ptr->interlaced != 0)
    {
       png_ptr->transformations |= PNG_INTERLACE;
-      return (7);
+      return 7;
    }
 
-   return (1);
+   return 1;
 }
 #endif
 
@@ -837,7 +837,7 @@ png_voidp PNGAPI
 png_get_user_transform_ptr(png_const_structrp png_ptr)
 {
    if (png_ptr == NULL)
-      return (NULL);
+      return NULL;
 
    return png_ptr->user_transform_ptr;
 }
diff --git a/pngwutil.c b/pngwutil.c
index 01f0607c7..14cc4ce36 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Copyright (c) 2018-2022 Cosmin Truta
+ * Copyright (c) 2018-2024 Cosmin Truta
  * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
  * Copyright (c) 1996-1997 Andreas Dilger
  * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
@@ -2311,7 +2311,7 @@ png_setup_sub_row(png_structrp png_ptr, png_uint_32 bpp,
         break;
    }
 
-   return (sum);
+   return sum;
 }
 
 static void /* PRIVATE */
@@ -2361,7 +2361,7 @@ png_setup_up_row(png_structrp png_ptr, size_t row_bytes, size_t lmins)
         break;
    }
 
-   return (sum);
+   return sum;
 }
 static void /* PRIVATE */
 png_setup_up_row_only(png_structrp png_ptr, size_t row_bytes)
@@ -2417,7 +2417,7 @@ png_setup_avg_row(png_structrp png_ptr, png_uint_32 bpp,
         break;
    }
 
-   return (sum);
+   return sum;
 }
 static void /* PRIVATE */
 png_setup_avg_row_only(png_structrp png_ptr, png_uint_32 bpp,
@@ -2500,7 +2500,7 @@ png_setup_paeth_row(png_structrp png_ptr, png_uint_32 bpp,
         break;
    }
 
-   return (sum);
+   return sum;
 }
 static void /* PRIVATE */
 png_setup_paeth_row_only(png_structrp png_ptr, png_uint_32 bpp,