diff --git a/src/syntax.c b/src/syntax.c
index fedce8d..98109e7 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -9786,7 +9786,7 @@
 }
 #endif
 
-#if defined(FEAT_TERMINAL) || defined(PROT)
+#if defined(FEAT_TERMINAL) || defined(PROTO)
     void
 syn_id2cterm_bg(int hl_id, int *fgp, int *bgp)
 {