diff --git a/src/libsecp256k1/rng.h b/src/libsecp256k1/rng.h
index 13daf08..103583f 100644
--- a/src/libsecp256k1/rng.h
+++ b/src/libsecp256k1/rng.h
@@ -4,6 +4,9 @@
  * EXAMPLES_COPYING or https://creativecommons.org/publicdomain/zero/1.0 *
  *************************************************************************/
 
+#ifndef LIBANTELOPE_LIBSECP256K1_RNG_H
+#define LIBANTELOPE_LIBSECP256K1_RNG_H
+
 /*
  * This file is an attempt at collecting best practice methods for obtaining randomness with different operating systems.
  * It may be out-of-date. Consult the documentation of the operating system before considering to use the methods below.
@@ -64,4 +67,6 @@ static int fill_random(unsigned char* data, size_t size) {
     }
 #endif
     return 0;
-}
\ No newline at end of file
+}
+
+#endif /* LIBANTELOPE_LIBSECP256K1_RNG_H */
\ No newline at end of file