diff --git a/x11-misc/dclock/dclock-2.2.2_p12.ebuild b/x11-misc/dclock/dclock-2.2.2_p12.ebuild
index 40e1bc5b55749..6ff7ea856b37b 100644
--- a/x11-misc/dclock/dclock-2.2.2_p12.ebuild
+++ b/x11-misc/dclock/dclock-2.2.2_p12.ebuild
@@ -45,6 +45,8 @@ src_prepare() {
 }
 
 src_configure() {
+	append-cflags -std=gnu89 # old codebase, incompatible with c2x
+
 	if use xft; then
 		append-cppflags \
 			-DXFT_SUPPORT \