diff --git a/ANNOUNCE b/ANNOUNCE
index 7db603526..44424e93a 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -350,6 +350,10 @@ Version 1.6.0beta20 [March 29, 2012]
     CVE-2011-3048).
 
 Version 1.6.0beta21 [April 13, 2012]
+  Revised scripts/makefile.darwin: use system zlib; remove quotes around
+    architecture list; add missing ppc architecture; add architecture options
+    to shared library link; don't try to create a shared lib based on missing
+    RELEASE variable.
   Enable png_set_check_for_invalid_index() for both read and write.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
diff --git a/CHANGES b/CHANGES
index b1fc74a5c..3d2a2f3ff 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4101,6 +4101,10 @@ Version 1.6.0beta20 [March 29, 2012]
     CVE-2011-3048).
 
 Version 1.6.0beta21 [April 13, 2012]
+  Revised scripts/makefile.darwin: use system zlib; remove quotes around
+    architecture list; add missing ppc architecture; add architecture options
+    to shared library link; don't try to create a shared lib based on missing
+    RELEASE variable.
   Enable png_set_check_for_invalid_index() for both read and write.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
diff --git a/scripts/makefile.darwin b/scripts/makefile.darwin
index 82d9d01b9..814fef502 100644
--- a/scripts/makefile.darwin
+++ b/scripts/makefile.darwin
@@ -15,10 +15,8 @@ prefix=/usr/local
 exec_prefix=$(prefix)
 
 # Where the zlib library and include files are located
-#ZLIBLIB=/usr/local/lib
-#ZLIBINC=/usr/local/include
-ZLIBLIB=../zlib
-ZLIBINC=../zlib
+ZLIBLIB=/usr/lib
+ZLIBINC=/usr/include
 
 # Library name:
 LIBNAME = libpng16
@@ -37,7 +35,7 @@ MKDIR_P=mkdir -p
 LN_SF=ln -sf
 RANLIB=ranlib
 RM_F=/bin/rm -f
-ARCH="-arch i386 -arch x86_64"
+ARCH=-arch ppc -arch i386 -arch x86_64
 
 # CFLAGS=-I$(ZLIBINC) -W -Wall -O3 -funroll-loops
 CFLAGS=-I$(ZLIBINC) -W -Wall -O -funroll-loops $(ARCH)
@@ -107,7 +105,7 @@ $(LIBSOMAJ): $(OBJSDLL)
 	$(CC) -dynamiclib \
 	 -install_name $(LIBPATH)/$(LIBSOMAJ) \
 	 -current_version 16 -compatibility_version 16 \
-	 -o $(LIBSOMAJ) \
+	 $(ARCH) -o $(LIBSOMAJ) \
 	 $(OBJSDLL) -L$(ZLIBLIB) -lz
 
 pngtest: pngtest.o $(LIBSO)
@@ -136,10 +134,10 @@ install-static: install-headers libpng.a
 install-shared: install-headers $(LIBSOMAJ) libpng.pc
 	-@if [ ! -d $(DL) ]; then $(MKDIR_P) $(DL); fi
 	-@$(RM_F) $(DL)/$(LIBSO)
-	-@$(RM_F) $(DL)/$(LIBSOREL)
+	-@$(RM_F) $(DL)/$(LIBSOMAJ)
 	-@$(RM_F) $(DL)/$(OLDSO)
-	cp $(LIBSOMAJ) $(DL)/$(LIBSOREL)
-	chmod 755 $(DL)/$(LIBSOREL)
+	cp $(LIBSOMAJ) $(DL)
+	chmod 755 $(DL)/$(LIBSOMAJ)
 	(cd $(DL); \
 	$(LN_SF) $(LIBSOREL) $(LIBSO); \
 	$(LN_SF) $(LIBSO) $(OLDSO))