diff --git a/crypto/siphash/siphash.c b/crypto/siphash/siphash.c
index ff84a29f821520113f76b7274c52a03425afbf33..be74a38d934df78aadd235bd15c91129d0b4b568 100644
--- a/crypto/siphash/siphash.c
+++ b/crypto/siphash/siphash.c
@@ -94,7 +94,19 @@ int SipHash_set_hash_size(SIPHASH *ctx, size_t hash_size)
         && hash_size != SIPHASH_MAX_DIGEST_SIZE)
         return 0;
 
-    ctx->hash_size = hash_size;
+    /*
+     * It's possible that the key was set first.  If the hash size changes,
+     * we need to adjust v1 (see SipHash_Init().
+     */
+
+    /* Start by adjusting the stored size, to make things easier */
+    ctx->hash_size = siphash_adjust_hash_size(ctx->hash_size);
+
+    /* Now, adjust ctx->v1 if the old and the new size differ */
+    if ((size_t)ctx->hash_size != hash_size) {
+        ctx->v1 ^= 0xee;
+        ctx->hash_size = hash_size;
+    }
     return 1;
 }
 
diff --git a/test/recipes/30-test_evp_data/evpmac.txt b/test/recipes/30-test_evp_data/evpmac.txt
index 4ec5fa425c49fc0953ecef8c119f8b95a8b5416c..2bcb3c33be16a63f644d256aac6f503d22c226e9 100644
--- a/test/recipes/30-test_evp_data/evpmac.txt
+++ b/test/recipes/30-test_evp_data/evpmac.txt
@@ -134,7 +134,7 @@ MAC = SipHash
 Ctrl = digestsize:8
 Key = 000102030405060708090A0B0C0D0E0F
 Input = 000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F202122232425262728292A2B2C2D2E2F303132333435363738393A3B3C3D3E
-Output = B96AB0B9D449A78A
+Output = 724506EB4C328A95
 
 # SIPHASH - default values: 2,4 rounds, explicit 16-byte mac