diff --git a/src/libsodium/include/sodium/randombytes.h b/src/libsodium/include/sodium/randombytes.h
index a03cc657..c83a4df5 100644
--- a/src/libsodium/include/sodium/randombytes.h
+++ b/src/libsodium/include/sodium/randombytes.h
@@ -53,7 +53,7 @@ SODIUM_EXPORT
 int randombytes_close(void);
 
 SODIUM_EXPORT
-int randombytes_set_implementation(randombytes_implementation *impl)
+int randombytes_set_implementation(const randombytes_implementation *impl)
             __attribute__ ((nonnull));
 
 SODIUM_EXPORT
diff --git a/src/libsodium/randombytes/randombytes.c b/src/libsodium/randombytes/randombytes.c
index 8ac085fc..2aa2762a 100644
--- a/src/libsodium/randombytes/randombytes.c
+++ b/src/libsodium/randombytes/randombytes.c
@@ -44,7 +44,7 @@ randombytes_init_if_needed(void)
 }
 
 int
-randombytes_set_implementation(randombytes_implementation *impl)
+randombytes_set_implementation(const randombytes_implementation *impl)
 {
     implementation = impl;