diff --git a/config.lib b/config.lib
--- a/config.lib
+++ b/config.lib
@@ -1455,12 +1455,16 @@ make_cflags_and_ldflags() {
 	fi
 
 	if [ $enable_debug -le 2 ]; then
-		if basename "$cc_host" | grep "gcc" &>/dev/null; then
+		cc_host_is_gcc=`basename "$cc_host" | grep "gcc" &>/dev/null`
+		if [ -n "$cc_host_is_gcc" ]; then
 			# Define only when compiling with GCC. Some GLIBC versions use GNU
 			# extensions in a way that breaks build with at least ICC.
 			# This requires -O1 or more, so debug level 3 (-O0) is excluded.
 			CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"
-
+		fi
+
+		cc_build_is_gcc=`basename "$cc_build" | grep "gcc" &>/dev/null`
+		if [ -n "$cc_build_is_gcc" ]; then
 			# Just add -O1 to the tools needed for building.
 			CFLAGS_BUILD="$CFLAGS_BUILD -D_FORTIFY_SOURCE=2 -O1"
 		fi