diff --git a/ext/gd/libgd/gd.c b/ext/gd/libgd/gd.c
index 4598081f40c..540605a9a53 100644
--- a/ext/gd/libgd/gd.c
+++ b/ext/gd/libgd/gd.c
@@ -9,8 +9,8 @@
 
 #ifdef _MSC_VER
 # if _MSC_VER >= 1300
-/* in MSVC.NET the these are available but only for __cplusplus and not _MSC_EXTENSIONS */
-#  ifdef _MSC_EXTENSIONS
+/* in MSVC.NET these are available but only for __cplusplus and not _MSC_EXTENSIONS */
+#  if !defined(_MSC_EXTENSIONS) && defined(__cplusplus)
 #   define HAVE_FABSF 1
 extern float fabsf(float x);
 #   define HAVE_FLOORF 1