diff --git a/term-utils/ttymsg.h b/term-utils/ttymsg.h
index 2cfa73027..8424ac40f 100644
--- a/term-utils/ttymsg.h
+++ b/term-utils/ttymsg.h
@@ -1,2 +1,6 @@
+#ifndef UTIL_LINUX_TERM_TTYMSG_H
+#define UTIL_LINUX_TERM_TTYMSG_H
+
 char *ttymsg(struct iovec *iov, size_t iovcnt, char *line, int tmout);
 
+#endif /* UTIL_LINUX_TERM_TTYMSG_H */