diff --git a/Gopkg.lock b/Gopkg.lock
index 627ae3a5b..496e8967c 100644
--- a/Gopkg.lock
+++ b/Gopkg.lock
@@ -91,8 +91,8 @@
     "ptypes/duration",
     "ptypes/timestamp"
   ]
-  revision = "b4deda0973fb4c70b50d226b1af49f3da59f5265"
-  version = "v1.1.0"
+  revision = "925541529c1fa6821df4e44ce2723319eb2be768"
+  version = "v1.0.0"
 
 [[projects]]
   branch = "master"
@@ -423,6 +423,6 @@
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "8c5f7f7b1a226e774353514c70f779e97d3311598076f510258b9ddcf87ed1f7"
+  inputs-digest = "c25289282b94abc7f0c390e592e5e1636b7f26cb4773863ac39cde7fdc7b5bdf"
   solver-name = "gps-cdcl"
   solver-version = 1
diff --git a/Gopkg.toml b/Gopkg.toml
index 32a000bb2..18e2767a9 100644
--- a/Gopkg.toml
+++ b/Gopkg.toml
@@ -43,7 +43,7 @@
 
 [[constraint]]
   name = "github.com/golang/protobuf"
-  version = "~1.1.0"
+  version = "~1.0.0"
 
 [[constraint]]
   name = "github.com/gorilla/websocket"
diff --git a/crypto/merkle/simple_tree_test.go b/crypto/merkle/simple_tree_test.go
index a721bccea..715242b67 100644
--- a/crypto/merkle/simple_tree_test.go
+++ b/crypto/merkle/simple_tree_test.go
@@ -6,8 +6,8 @@ import (
 	cmn "github.com/tendermint/tmlibs/common"
 	. "github.com/tendermint/tmlibs/test"
 
-	"testing"
 	"github.com/tendermint/tendermint/crypto/tmhash"
+	"testing"
 )
 
 type testItem []byte
@@ -39,16 +39,16 @@ func TestSimpleProof(t *testing.T) {
 		proof := proofs[i]
 
 		// Verify success
-		ok := proof.Verify(i, total, itemHash, rootHash)
-		if !ok {
-			t.Errorf("Verification failed for index %v.", i)
+		err := proof.Verify(rootHash, i, total, itemHash)
+		if err != nil {
+			t.Errorf("Verification failed: %v.", err)
 		}
 
 		// Wrong item index should make it fail
 		{
-			ok = proof.Verify((i+1)%total, total, itemHash, rootHash)
-			if ok {
-				t.Errorf("Expected verification to fail for wrong index %v.", i)
+			err = proof.Verify(rootHash, (i+1)%total, total, itemHash)
+			if err == nil {
+				t.Errorf("Expected verification to fail for wrong index %v", i)
 			}
 		}
 
@@ -56,9 +56,9 @@ func TestSimpleProof(t *testing.T) {
 		origAunts := proof.Aunts
 		proof.Aunts = append(proof.Aunts, cmn.RandBytes(32))
 		{
-			ok = proof.Verify(i, total, itemHash, rootHash)
-			if ok {
-				t.Errorf("Expected verification to fail for wrong trail length.")
+			err = proof.Verify(rootHash, i, total, itemHash)
+			if err == nil {
+				t.Errorf("Expected verification to fail for wrong trail length")
 			}
 		}
 		proof.Aunts = origAunts
@@ -66,22 +66,22 @@ func TestSimpleProof(t *testing.T) {
 		// Trail too short should make it fail
 		proof.Aunts = proof.Aunts[0 : len(proof.Aunts)-1]
 		{
-			ok = proof.Verify(i, total, itemHash, rootHash)
-			if ok {
-				t.Errorf("Expected verification to fail for wrong trail length.")
+			err = proof.Verify(rootHash, i, total, itemHash)
+			if err == nil {
+				t.Errorf("Expected verification to fail for wrong trail length")
 			}
 		}
 		proof.Aunts = origAunts
 
 		// Mutating the itemHash should make it fail.
-		ok = proof.Verify(i, total, MutateByteSlice(itemHash), rootHash)
-		if ok {
+		err = proof.Verify(rootHash, i, total, MutateByteSlice(itemHash))
+		if err == nil {
 			t.Errorf("Expected verification to fail for mutated leaf hash")
 		}
 
 		// Mutating the rootHash should make it fail.
-		ok = proof.Verify(i, total, itemHash, MutateByteSlice(rootHash))
-		if ok {
+		err = proof.Verify(MutateByteSlice(rootHash), i, total, itemHash)
+		if err == nil {
 			t.Errorf("Expected verification to fail for mutated root hash")
 		}
 	}