diff --git a/configure.ac b/configure.ac
index 807804e5..f4a947d2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1275,11 +1275,14 @@ if test "${enable_pkcs11}" = "yes"; then
 	)
 fi
 
+# When testing a compiler option, we add -Werror to force
+# an error when the option is unsupported. This is not
+# required for gcc, but come compilers such as clang needs it.
 AC_DEFUN([ACL_CHECK_ADD_COMPILE_FLAGS], [
     old_cflags="$CFLAGS"
-    CFLAGS="$1 $CFLAGS"
-    AC_MSG_CHECKING([whether the compiler acceppts $1])
-    AC_COMPILE_IFELSE([AC_LANG_PROGRAM()], [AC_MSG_RESULT([yes])],
+    CFLAGS="$1 -Werror $CFLAGS"
+    AC_MSG_CHECKING([whether the compiler accepts $1])
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM()], [AC_MSG_RESULT([yes])]; CFLAGS="$1 $old_cflags",
         [AC_MSG_RESULT([no]); CFLAGS="$old_cflags"])]
 )