diff --git a/usr.bin/indent/io.c b/usr.bin/indent/io.c
index 1e36582d5bf8..dda626512707 100644
--- a/usr.bin/indent/io.c
+++ b/usr.bin/indent/io.c
@@ -581,12 +581,12 @@ diag2(int level, const char *msg)
 	found_err = 1;
     if (output == stdout) {
 	fprintf(stdout, "/**INDENT** %s@%d: ", level == 0 ? "Warning" : "Error", line_no);
-	fprintf(stdout, msg);
+	fprintf(stdout, "%s", msg);
 	fprintf(stdout, " */\n");
     }
     else {
 	fprintf(stderr, "%s@%d: ", level == 0 ? "Warning" : "Error", line_no);
-	fprintf(stderr, msg);
+	fprintf(stderr, "%s", msg);
 	fprintf(stderr, "\n");
     }
 }