diff --git a/src/syntax.c b/src/syntax.c
index 54a5061..9058368 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -1700,7 +1700,7 @@
 	return 0;
 
     /* After 'synmaxcol' the attribute is always zero. */
-    if (syn_buf->b_p_smc > 0 && col >= syn_buf->b_p_smc)
+    if (syn_buf->b_p_smc > 0 && col >= (colnr_T)syn_buf->b_p_smc)
     {
 	clear_current_state();
 #ifdef FEAT_EVAL