diff --git a/configure b/configure
index 1b6f68b691..8ad42bc2a6 100755
--- a/configure
+++ b/configure
@@ -3520,7 +3520,7 @@ if test "$gcov" = "yes" ; then
   CFLAGS="-fprofile-arcs -ftest-coverage -g $CFLAGS"
   LDFLAGS="-fprofile-arcs -ftest-coverage $LDFLAGS"
 elif test "$debug" = "no" ; then
-  CFLAGS="-O2 -D_FORTIFY_SOURCE=2 $CFLAGS"
+  CFLAGS="-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
 fi