diff --git a/include/nana/config.hpp b/include/nana/config.hpp
index acef5d8c..e97c70f6 100644
--- a/include/nana/config.hpp
+++ b/include/nana/config.hpp
@@ -117,7 +117,7 @@
 //#define NANA_ENABLE_PNG	//!
 //#define USE_LIBPNG_FROM_OS // Un-Comment it to use libpng from operating system.
 #if defined(NANA_ENABLE_PNG)
-	#if not defined(USE_LIBPNG_FROM_OS)
+	#if !defined(USE_LIBPNG_FROM_OS)
 		#define NANA_LIBPNG
 	#endif
 #endif
@@ -129,7 +129,7 @@
 //#define NANA_ENABLE_JPEG	//!
 //#define USE_LIBJPEG_FROM_OS // Un-Comment it to use libjpeg from operating system.
 #if defined(NANA_ENABLE_JPEG)
-	#if not defined(USE_LIBJPEG_FROM_OS)
+	#if !defined(USE_LIBJPEG_FROM_OS)
 		#define NANA_LIBJPEG
 	#endif
 #endif