diff --git a/rtcore.h b/rtcore.h
index 1e95491..e729ce0 100644
--- a/rtcore.h
+++ b/rtcore.h
@@ -215,7 +215,7 @@ enum
 RTC_API void *ArenaAlloc(arena *a, isize size, isize align, isize n, int flags);
 
 /* Compute a simple, non-cryptographic hash */
-RTC_API u64 SimpleHash(byte *data, isize len);
+RTC_API u64 SimpleHash(const byte *data, isize len);
 
 /* String type */
 typedef struct s8
@@ -490,7 +490,7 @@ ArenaAlloc(arena *a, isize size, isize align, isize n, int flags)
 
 /* Basic hash */
 RTC_API u64
-SimpleHash(byte *data, isize len)
+SimpleHash(const byte *data, isize len)
 {
 	u64 hash = 0xcbf29ce484222325;
 	for (isize i = 0; i < len; ++i)