diff --git a/Crypto/Hash/Keccak.hs b/Crypto/Hash/Keccak.hs
index 296947c..bd51abd 100644
--- a/Crypto/Hash/Keccak.hs
+++ b/Crypto/Hash/Keccak.hs
@@ -28,7 +28,7 @@ instance HashAlgorithm Keccak_224 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_keccak_init p 224
     hashInternalUpdate        = c_keccak_update
-    hashInternalFinalize      = c_keccak_finalize
+    hashInternalFinalize p    = c_keccak_finalize p 224
 
 -- | Keccak (256 bits) cryptographic hash algorithm
 data Keccak_256 = Keccak_256
@@ -40,7 +40,7 @@ instance HashAlgorithm Keccak_256 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_keccak_init p 256
     hashInternalUpdate        = c_keccak_update
-    hashInternalFinalize      = c_keccak_finalize
+    hashInternalFinalize p    = c_keccak_finalize p 256
 
 -- | Keccak (384 bits) cryptographic hash algorithm
 data Keccak_384 = Keccak_384
@@ -52,7 +52,7 @@ instance HashAlgorithm Keccak_384 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_keccak_init p 384
     hashInternalUpdate        = c_keccak_update
-    hashInternalFinalize      = c_keccak_finalize
+    hashInternalFinalize p    = c_keccak_finalize p 384
 
 -- | Keccak (512 bits) cryptographic hash algorithm
 data Keccak_512 = Keccak_512
@@ -64,7 +64,7 @@ instance HashAlgorithm Keccak_512 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_keccak_init p 512
     hashInternalUpdate        = c_keccak_update
-    hashInternalFinalize      = c_keccak_finalize
+    hashInternalFinalize p    = c_keccak_finalize p 512
 
 
 foreign import ccall unsafe "cryptonite_keccak_init"
@@ -74,4 +74,4 @@ foreign import ccall "cryptonite_keccak_update"
     c_keccak_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()
 
 foreign import ccall unsafe "cryptonite_keccak_finalize"
-    c_keccak_finalize :: Ptr (Context a) -> Ptr (Digest a) -> IO ()
+    c_keccak_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()
diff --git a/Crypto/Hash/SHA3.hs b/Crypto/Hash/SHA3.hs
index 7ecdfa8..ded49ee 100644
--- a/Crypto/Hash/SHA3.hs
+++ b/Crypto/Hash/SHA3.hs
@@ -28,7 +28,7 @@ instance HashAlgorithm SHA3_224 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_sha3_init p 224
     hashInternalUpdate        = c_sha3_update
-    hashInternalFinalize      = c_sha3_finalize
+    hashInternalFinalize p    = c_sha3_finalize p 224
 
 -- | SHA3 (256 bits) cryptographic hash algorithm
 data SHA3_256 = SHA3_256
@@ -40,7 +40,7 @@ instance HashAlgorithm SHA3_256 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_sha3_init p 256
     hashInternalUpdate        = c_sha3_update
-    hashInternalFinalize      = c_sha3_finalize
+    hashInternalFinalize p    = c_sha3_finalize p 256
 
 -- | SHA3 (384 bits) cryptographic hash algorithm
 data SHA3_384 = SHA3_384
@@ -52,7 +52,7 @@ instance HashAlgorithm SHA3_384 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_sha3_init p 384
     hashInternalUpdate        = c_sha3_update
-    hashInternalFinalize      = c_sha3_finalize
+    hashInternalFinalize p    = c_sha3_finalize p 384
 
 -- | SHA3 (512 bits) cryptographic hash algorithm
 data SHA3_512 = SHA3_512
@@ -64,7 +64,7 @@ instance HashAlgorithm SHA3_512 where
     hashInternalContextSize _ = 360
     hashInternalInit p        = c_sha3_init p 512
     hashInternalUpdate        = c_sha3_update
-    hashInternalFinalize      = c_sha3_finalize
+    hashInternalFinalize p    = c_sha3_finalize p 512
 
 
 foreign import ccall unsafe "cryptonite_sha3_init"
@@ -74,4 +74,4 @@ foreign import ccall "cryptonite_sha3_update"
     c_sha3_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()
 
 foreign import ccall unsafe "cryptonite_sha3_finalize"
-    c_sha3_finalize :: Ptr (Context a) -> Ptr (Digest a) -> IO ()
+    c_sha3_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()
diff --git a/Crypto/Hash/SHA512t.hs b/Crypto/Hash/SHA512t.hs
index 5e0f7fc..e9e6ac7 100644
--- a/Crypto/Hash/SHA512t.hs
+++ b/Crypto/Hash/SHA512t.hs
@@ -28,7 +28,7 @@ instance HashAlgorithm SHA512t_224 where
     hashInternalContextSize _ = 264
     hashInternalInit p        = c_sha512t_init p 224
     hashInternalUpdate        = c_sha512t_update
-    hashInternalFinalize      = c_sha512t_finalize
+    hashInternalFinalize p    = c_sha512t_finalize p 224
 
 -- | SHA512t (256 bits) cryptographic hash algorithm
 data SHA512t_256 = SHA512t_256
@@ -40,7 +40,7 @@ instance HashAlgorithm SHA512t_256 where
     hashInternalContextSize _ = 264
     hashInternalInit p        = c_sha512t_init p 256
     hashInternalUpdate        = c_sha512t_update
-    hashInternalFinalize      = c_sha512t_finalize
+    hashInternalFinalize p    = c_sha512t_finalize p 256
 
 
 foreign import ccall unsafe "cryptonite_sha512t_init"
@@ -50,4 +50,4 @@ foreign import ccall "cryptonite_sha512t_update"
     c_sha512t_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()
 
 foreign import ccall unsafe "cryptonite_sha512t_finalize"
-    c_sha512t_finalize :: Ptr (Context a) -> Ptr (Digest a) -> IO ()
+    c_sha512t_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()
diff --git a/Crypto/Hash/Skein256.hs b/Crypto/Hash/Skein256.hs
index b5a97fb..883b0f7 100644
--- a/Crypto/Hash/Skein256.hs
+++ b/Crypto/Hash/Skein256.hs
@@ -28,7 +28,7 @@ instance HashAlgorithm Skein256_224 where
     hashInternalContextSize _ = 96
     hashInternalInit p        = c_skein256_init p 224
     hashInternalUpdate        = c_skein256_update
-    hashInternalFinalize      = c_skein256_finalize
+    hashInternalFinalize p    = c_skein256_finalize p 224
 
 -- | Skein256 (256 bits) cryptographic hash algorithm
 data Skein256_256 = Skein256_256
@@ -40,7 +40,7 @@ instance HashAlgorithm Skein256_256 where
     hashInternalContextSize _ = 96
     hashInternalInit p        = c_skein256_init p 256
     hashInternalUpdate        = c_skein256_update
-    hashInternalFinalize      = c_skein256_finalize
+    hashInternalFinalize p    = c_skein256_finalize p 256
 
 
 foreign import ccall unsafe "cryptonite_skein256_init"
@@ -50,4 +50,4 @@ foreign import ccall "cryptonite_skein256_update"
     c_skein256_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()
 
 foreign import ccall unsafe "cryptonite_skein256_finalize"
-    c_skein256_finalize :: Ptr (Context a) -> Ptr (Digest a) -> IO ()
+    c_skein256_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()
diff --git a/Crypto/Hash/Skein512.hs b/Crypto/Hash/Skein512.hs
index bd2de5d..de2367d 100644
--- a/Crypto/Hash/Skein512.hs
+++ b/Crypto/Hash/Skein512.hs
@@ -28,7 +28,7 @@ instance HashAlgorithm Skein512_224 where
     hashInternalContextSize _ = 160
     hashInternalInit p        = c_skein512_init p 224
     hashInternalUpdate        = c_skein512_update
-    hashInternalFinalize      = c_skein512_finalize
+    hashInternalFinalize p    = c_skein512_finalize p 224
 
 -- | Skein512 (256 bits) cryptographic hash algorithm
 data Skein512_256 = Skein512_256
@@ -40,7 +40,7 @@ instance HashAlgorithm Skein512_256 where
     hashInternalContextSize _ = 160
     hashInternalInit p        = c_skein512_init p 256
     hashInternalUpdate        = c_skein512_update
-    hashInternalFinalize      = c_skein512_finalize
+    hashInternalFinalize p    = c_skein512_finalize p 256
 
 -- | Skein512 (384 bits) cryptographic hash algorithm
 data Skein512_384 = Skein512_384
@@ -52,7 +52,7 @@ instance HashAlgorithm Skein512_384 where
     hashInternalContextSize _ = 160
     hashInternalInit p        = c_skein512_init p 384
     hashInternalUpdate        = c_skein512_update
-    hashInternalFinalize      = c_skein512_finalize
+    hashInternalFinalize p    = c_skein512_finalize p 384
 
 -- | Skein512 (512 bits) cryptographic hash algorithm
 data Skein512_512 = Skein512_512
@@ -64,7 +64,7 @@ instance HashAlgorithm Skein512_512 where
     hashInternalContextSize _ = 160
     hashInternalInit p        = c_skein512_init p 512
     hashInternalUpdate        = c_skein512_update
-    hashInternalFinalize      = c_skein512_finalize
+    hashInternalFinalize p    = c_skein512_finalize p 512
 
 
 foreign import ccall unsafe "cryptonite_skein512_init"
@@ -74,4 +74,4 @@ foreign import ccall "cryptonite_skein512_update"
     c_skein512_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()
 
 foreign import ccall unsafe "cryptonite_skein512_finalize"
-    c_skein512_finalize :: Ptr (Context a) -> Ptr (Digest a) -> IO ()
+    c_skein512_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()
diff --git a/cbits/cryptonite_keccak.c b/cbits/cryptonite_keccak.c
index 801be92..5e13551 100644
--- a/cbits/cryptonite_keccak.c
+++ b/cbits/cryptonite_keccak.c
@@ -135,7 +135,7 @@ void cryptonite_keccak_update(struct keccak_ctx *ctx, uint8_t *data, uint32_t le
 	}
 }
 
-void cryptonite_keccak_finalize(struct keccak_ctx *ctx, uint8_t *out)
+void cryptonite_keccak_finalize(struct keccak_ctx *ctx, uint32_t hashlen, uint8_t *out)
 {
 	uint64_t w[25];
 
diff --git a/cbits/cryptonite_keccak.h b/cbits/cryptonite_keccak.h
index 9f77bb4..c83f4b6 100644
--- a/cbits/cryptonite_keccak.h
+++ b/cbits/cryptonite_keccak.h
@@ -40,6 +40,6 @@ struct keccak_ctx
 
 void cryptonite_keccak_init(struct keccak_ctx *ctx, uint32_t hashlen);
 void cryptonite_keccak_update(struct keccak_ctx *ctx, uint8_t *data, uint32_t len);
-void cryptonite_keccak_finalize(struct keccak_ctx *ctx, uint8_t *out);
+void cryptonite_keccak_finalize(struct keccak_ctx *ctx, uint32_t hashlen, uint8_t *out);
 
 #endif
diff --git a/cbits/cryptonite_sha3.c b/cbits/cryptonite_sha3.c
index 13bfea9..923150a 100644
--- a/cbits/cryptonite_sha3.c
+++ b/cbits/cryptonite_sha3.c
@@ -135,7 +135,7 @@ void cryptonite_sha3_update(struct sha3_ctx *ctx, const uint8_t *data, uint32_t
 	}
 }
 
-void cryptonite_sha3_finalize(struct sha3_ctx *ctx, uint8_t *out)
+void cryptonite_sha3_finalize(struct sha3_ctx *ctx, uint32_t hashlen, uint8_t *out)
 {
 	uint64_t w[25];
 
@@ -155,5 +155,5 @@ void cryptonite_sha3_finalize(struct sha3_ctx *ctx, uint8_t *out)
 
 	/* output */
 	cpu_to_le64_array(w, ctx->state, 25);
-	memcpy(out, w, ctx->hashlen);
+	memcpy(out, w, hashlen / 8);
 }
diff --git a/cbits/cryptonite_sha3.h b/cbits/cryptonite_sha3.h
index 3b46441..1f78674 100644
--- a/cbits/cryptonite_sha3.h
+++ b/cbits/cryptonite_sha3.h
@@ -40,6 +40,6 @@ struct sha3_ctx
 
 void cryptonite_sha3_init(struct sha3_ctx *ctx, uint32_t hashlen);
 void cryptonite_sha3_update(struct sha3_ctx *ctx, const uint8_t *data, uint32_t len);
-void cryptonite_sha3_finalize(struct sha3_ctx *ctx, uint8_t *out);
+void cryptonite_sha3_finalize(struct sha3_ctx *ctx, uint32_t hashlen, uint8_t *out);
 
 #endif
diff --git a/cbits/cryptonite_sha512.c b/cbits/cryptonite_sha512.c
index f86042a..6adf028 100644
--- a/cbits/cryptonite_sha512.c
+++ b/cbits/cryptonite_sha512.c
@@ -196,15 +196,15 @@ void cryptonite_sha512_finalize(struct sha512_ctx *ctx, uint8_t *out)
 
 #include <stdio.h>
 
-void cryptonite_sha512t_init(struct sha512t_ctx *tctx, int t)
+void cryptonite_sha512t_init(struct sha512t_ctx *tctx, uint32_t hashlen)
 {
 	struct sha512_ctx *ctx = &tctx->ctx;
 	memset(ctx, 0, sizeof(*ctx));
-	if (t >= 512)
+	if (hashlen >= 512)
 		return;
-	tctx->t = t;
+	tctx->t = hashlen;
 
-	switch (t) {
+	switch (hashlen) {
 	case 224:
 		ctx->h[0] = 0x8c3d37c819544da2ULL;
 		ctx->h[1] = 0x73e1996689dcd4d6ULL;
@@ -234,7 +234,7 @@ void cryptonite_sha512t_init(struct sha512t_ctx *tctx, int t)
 		for (i = 0; i < 8; i++)
 			ctx->h[i] ^= 0xa5a5a5a5a5a5a5a5ULL;
 
-		i = sprintf(buf, "SHA-512/%d", t);
+		i = sprintf(buf, "SHA-512/%d", hashlen);
 		cryptonite_sha512_update(ctx, (uint8_t *) buf, i);
 		cryptonite_sha512_finalize(ctx, out);
 
@@ -251,7 +251,7 @@ void cryptonite_sha512t_update(struct sha512t_ctx *ctx, const uint8_t *data, uin
 	return cryptonite_sha512_update(&ctx->ctx, data, len);
 }
 
-void cryptonite_sha512t_finalize(struct sha512t_ctx *ctx, uint8_t *out)
+void cryptonite_sha512t_finalize(struct sha512t_ctx *ctx, uint32_t hashlen, uint8_t *out)
 {
 	uint8_t intermediate[SHA512_DIGEST_SIZE];
 
diff --git a/cbits/cryptonite_sha512.h b/cbits/cryptonite_sha512.h
index 4b547ea..a762584 100644
--- a/cbits/cryptonite_sha512.h
+++ b/cbits/cryptonite_sha512.h
@@ -58,8 +58,8 @@ void cryptonite_sha512_update(struct sha512_ctx *ctx, const uint8_t *data, uint3
 void cryptonite_sha512_finalize(struct sha512_ctx *ctx, uint8_t *out);
 
 /* only multiples of 8 are supported as valid t values */
-void cryptonite_sha512t_init(struct sha512t_ctx *ctx, int t);
+void cryptonite_sha512t_init(struct sha512t_ctx *ctx, uint32_t hashlen);
 void cryptonite_sha512t_update(struct sha512t_ctx *ctx, const uint8_t *data, uint32_t len);
-void cryptonite_sha512t_finalize(struct sha512t_ctx *ctx, uint8_t *out);
+void cryptonite_sha512t_finalize(struct sha512t_ctx *ctx, uint32_t hashlen, uint8_t *out);
 
 #endif
diff --git a/cbits/cryptonite_skein256.c b/cbits/cryptonite_skein256.c
index a2f6e07..d851898 100644
--- a/cbits/cryptonite_skein256.c
+++ b/cbits/cryptonite_skein256.c
@@ -155,7 +155,7 @@ void cryptonite_skein256_update(struct skein256_ctx *ctx, const uint8_t *data, u
 	}
 }
 
-void cryptonite_skein256_finalize(struct skein256_ctx *ctx, uint8_t *out)
+void cryptonite_skein256_finalize(struct skein256_ctx *ctx, uint32_t hashlen, uint8_t *out)
 {
 	uint32_t outsize;
 	uint64_t *p = (uint64_t *) out;
diff --git a/cbits/cryptonite_skein256.h b/cbits/cryptonite_skein256.h
index eaaa037..f23b43c 100644
--- a/cbits/cryptonite_skein256.h
+++ b/cbits/cryptonite_skein256.h
@@ -40,6 +40,6 @@ struct skein256_ctx
 
 void cryponite_skein256_init(struct skein256_ctx *ctx, uint32_t hashlen);
 void cryponite_skein256_update(struct skein256_ctx *ctx, const uint8_t *data, uint32_t len);
-void cryponite_skein256_finalize(struct skein256_ctx *ctx, uint8_t *out);
+void cryponite_skein256_finalize(struct skein256_ctx *ctx, uint32_t hashlen, uint8_t *out);
 
 #endif
diff --git a/cbits/cryptonite_skein512.c b/cbits/cryptonite_skein512.c
index 5e38e51..8f411ff 100644
--- a/cbits/cryptonite_skein512.c
+++ b/cbits/cryptonite_skein512.c
@@ -173,7 +173,7 @@ void cryptonite_skein512_update(struct skein512_ctx *ctx, const uint8_t *data, u
 	}
 }
 
-void cryptonite_skein512_finalize(struct skein512_ctx *ctx, uint8_t *out)
+void cryptonite_skein512_finalize(struct skein512_ctx *ctx, uint32_t hashlen, uint8_t *out)
 {
 	uint32_t outsize;
 	uint64_t *p = (uint64_t *) out;
diff --git a/cbits/cryptonite_skein512.h b/cbits/cryptonite_skein512.h
index 069500c..e3f4ab6 100644
--- a/cbits/cryptonite_skein512.h
+++ b/cbits/cryptonite_skein512.h
@@ -40,6 +40,6 @@ struct skein512_ctx
 
 void cryponite_skein512_init(struct skein512_ctx *ctx, uint32_t hashlen);
 void cryponite_skein512_update(struct skein512_ctx *ctx, const uint8_t *data, uint32_t len);
-void cryponite_skein512_finalize(struct skein512_ctx *ctx, uint8_t *out);
+void cryponite_skein512_finalize(struct skein512_ctx *ctx, uint32_t hashlen, uint8_t *out);
 
 #endif
diff --git a/gen/template/hash-len.hs b/gen/template/hash-len.hs
index df2a7f9..9f7381d 100644
--- a/gen/template/hash-len.hs
+++ b/gen/template/hash-len.hs
@@ -28,7 +28,7 @@ instance HashAlgorithm %%MODULENAME%%_%%CUSTOM_BITSIZE%% where
     hashInternalContextSize _ = %%CTX_SIZE_BYTES%%
     hashInternalInit p        = c_%%HASHNAME%%_init p %%CUSTOM_BITSIZE%%
     hashInternalUpdate        = c_%%HASHNAME%%_update
-    hashInternalFinalize      = c_%%HASHNAME%%_finalize
+    hashInternalFinalize p    = c_%%HASHNAME%%_finalize p %%CUSTOM_BITSIZE%%
 %{CUSTOMIZABLE%}
 
 foreign import ccall unsafe "cryptonite_%%HASHNAME%%_init"
@@ -38,4 +38,4 @@ foreign import ccall "cryptonite_%%HASHNAME%%_update"
     c_%%HASHNAME%%_update :: Ptr (Context a) -> Ptr Word8 -> Word32 -> IO ()
 
 foreign import ccall unsafe "cryptonite_%%HASHNAME%%_finalize"
-    c_%%HASHNAME%%_finalize :: Ptr (Context a) -> Ptr (Digest a) -> IO ()
+    c_%%HASHNAME%%_finalize :: Ptr (Context a) -> Word32 -> Ptr (Digest a) -> IO ()