diff --git a/CMakeLists.txt b/CMakeLists.txt
index a13c628..1d8d1a6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -348,7 +348,9 @@
 # fixed size integral types
 
 IF(HAVE_INTTYPES_H_LIBZIP)
-  SET(LIBZIP_TYPES_INCLUDE "#define __STDC_FORMAT_MACROS 1
+  SET(LIBZIP_TYPES_INCLUDE "#if !defined(__STDC_FORMAT_MACROS)
+#define __STDC_FORMAT_MACROS 1
+#endif
 #include <inttypes.h>")
 ELSEIF(HAVE_STDINT_H_LIBZIP)
   SET(LIBZIP_TYPES_INCLUDE "#include <stdint.h>")