diff --git a/trezor-crypto/crypto/scrypt.c b/trezor-crypto/crypto/scrypt.c
index c1856dcbda5..4e94beab0e8 100644
--- a/trezor-crypto/crypto/scrypt.c
+++ b/trezor-crypto/crypto/scrypt.c
@@ -42,7 +42,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-static void blkcpy(void *, void *, size_t);
+static void blkcpy(uint32_t *, const uint32_t *, size_t);
 static void blkxor(void *, void *, size_t);
 static void salsa20_8(uint32_t[16]);
 static void blockmix_salsa8(uint32_t *, uint32_t *, uint32_t *, size_t);
@@ -50,15 +50,12 @@ static uint64_t integerify(void *, size_t);
 static void smix(uint8_t *, size_t, uint64_t, uint32_t *, uint32_t *);
 
 static void
-blkcpy(void * dest, void * src, size_t len)
+blkcpy(uint32_t * dest, const uint32_t * src, size_t len)
 {
-	size_t * D = dest;
-	size_t * S = src;
-	size_t L = len / sizeof(size_t);
-	size_t i;
+    size_t L = len / sizeof(uint32_t);
 
-	for (i = 0; i < L; i++)
-		D[i] = S[i];
+    for (size_t i = 0; i < L; i++)
+        dest[i] = src[i];
 }
 
 static void