diff --git a/compat_arc4random.c b/compat_arc4random.c
index 2c7f423..16e0523 100644
--- a/compat_arc4random.c
+++ b/compat_arc4random.c
@@ -285,6 +285,10 @@ struct rand_state
 };
 typedef struct rand_state rand_state;
 
+/* declaration required for mac os x */
+/* kernel entropy */
+extern int getentropy(void* buf, size_t n);
+
 #define minimum(a, b) ((a) < (b) ? (a) : (b))
 
 static inline void
diff --git a/compats.c b/compats.c
index 40f0592..861462c 100644
--- a/compats.c
+++ b/compats.c
@@ -287,6 +287,10 @@ struct rand_state
 };
 typedef struct rand_state rand_state;
 
+/* declaration required for mac os x */
+/* kernel entropy */
+extern int getentropy(void* buf, size_t n);
+
 #define minimum(a, b) ((a) < (b) ? (a) : (b))
 
 static inline void