diff --git a/configure.ac b/configure.ac
index a80c05d..938c019 100644
--- a/configure.ac
+++ b/configure.ac
@@ -19,7 +19,9 @@
 ]], [[
     return 0;
 ]])],
+              [je_cv_cflags_appended=$1]
               AC_MSG_RESULT([yes]),
+              [je_cv_cflags_appended=]
               AC_MSG_RESULT([no])
               [CFLAGS="${TCFLAGS}"]
 )
@@ -128,6 +130,9 @@
   no_CFLAGS="yes"
   if test "x$GCC" = "xyes" ; then
     JE_CFLAGS_APPEND([-std=gnu99])
+    if test "x$je_cv_cflags_appended" = "x-std=gnu99" ; then
+      AC_DEFINE_UNQUOTED([JEMALLOC_HAS_RESTRICT])
+    fi
     JE_CFLAGS_APPEND([-Wall])
     JE_CFLAGS_APPEND([-pipe])
     JE_CFLAGS_APPEND([-g3])