diff --git a/src/syntax.c b/src/syntax.c
index be79c2c..3ac43d7 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -3433,7 +3433,7 @@
     if (!eap->skip)
     {
 	STRCPY(buf, "so ");
-	sprintf((char *)buf + 3, SYNTAX_FNAME, name);
+	vim_snprintf((char *)buf + 3, sizeof(buf) - 3, SYNTAX_FNAME, name);
 	do_cmdline_cmd(buf);
     }
 }