diff --git a/libavutil/rc4.h b/libavutil/rc4.h
index e4546e3e9d..d3b8e6cb81 100644
--- a/libavutil/rc4.h
+++ b/libavutil/rc4.h
@@ -19,7 +19,7 @@
  */
 
 #ifndef RC4_H
-#ifndef RC4_H
+#define RC4_H
 
 void ff_rc4_enc(const uint8_t *key, int keylen, uint8_t *data, int datalen);