1 files changed, 5 insertions, 0 deletions
diff --git a/configure b/configure
index f6cac34fbf..d42fb3caf3 100755
--- a/configure
+++ b/configure
@@ -4232,6 +4232,11 @@ case $_opengl_mode in
 		echo "yes (OpenGL ES 2)"
 		add_line_to_config_h "#define USE_GLES_MODE 2"
 		;;
+
+	*)
+		echo "invalid mode specification '$_opengl_mode'. Aborting."
+		exit 1
+		;;
 esac
 
 define_in_config_if_yes "$_opengl" "USE_OPENGL"