--- src/gpg-error.h.in
+++ src/gpg-error.h.in
@@ -141,7 +141,7 @@
 
 
 /* GCC feature test.  */
-#if __GNUC__
+#if defined __GNUC__
 # define _GPG_ERR_GCC_VERSION (__GNUC__ * 10000 \
                                + __GNUC_MINOR__ * 100 \
                                + __GNUC_PATCHLEVEL__)