diff --git a/types/genesis_test.go b/types/genesis_test.go
index 0ffce4b5..0028f51e 100644
--- a/types/genesis_test.go
+++ b/types/genesis_test.go
@@ -60,31 +60,3 @@ func TestGenesis(t *testing.T) {
 	genDoc, err = GenesisDocFromJSON(genDocBytes)
 	assert.Error(t, err, "expected error for genDoc json with block size of 0")
 }
-
-func newConsensusParams(blockSize, partSize int) ConsensusParams {
-	return ConsensusParams{
-		BlockSizeParams:   BlockSizeParams{MaxBytes: blockSize},
-		BlockGossipParams: BlockGossipParams{BlockPartSizeBytes: partSize},
-	}
-
-}
-
-func TestConsensusParams(t *testing.T) {
-
-	testCases := []struct {
-		params ConsensusParams
-		valid  bool
-	}{
-		{newConsensusParams(1, 1), true},
-		{newConsensusParams(1, 0), false},
-		{newConsensusParams(0, 1), false},
-		{newConsensusParams(0, 0), false},
-	}
-	for _, testCase := range testCases {
-		if testCase.valid {
-			assert.NoError(t, testCase.params.Validate(), "expected no error for valid params")
-		} else {
-			assert.Error(t, testCase.params.Validate(), "expected error for non valid params")
-		}
-	}
-}
diff --git a/types/params.go b/types/params.go
index 495d1fd4..322cba61 100644
--- a/types/params.go
+++ b/types/params.go
@@ -18,7 +18,7 @@ type ConsensusParams struct {
 
 // BlockSizeParams contain limits on the block size.
 type BlockSizeParams struct {
-	MaxBytes int `json:"max_bytes"` // NOTE: must not be 0
+	MaxBytes int `json:"max_bytes"` // NOTE: must not be 0 nor greater than 100MB
 	MaxTxs   int `json:"max_txs"`
 	MaxGas   int `json:"max_gas"`
 }
diff --git a/types/params_test.go b/types/params_test.go
new file mode 100644
index 00000000..507c8513
--- /dev/null
+++ b/types/params_test.go
@@ -0,0 +1,40 @@
+package types
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func newConsensusParams(blockSize, partSize int) ConsensusParams {
+	return ConsensusParams{
+		BlockSizeParams:   BlockSizeParams{MaxBytes: blockSize},
+		BlockGossipParams: BlockGossipParams{BlockPartSizeBytes: partSize},
+	}
+}
+
+func TestConsensusParamsValidation(t *testing.T) {
+	testCases := []struct {
+		params ConsensusParams
+		valid  bool
+	}{
+		{newConsensusParams(1, 1), true},
+		{newConsensusParams(1, 0), false},
+		{newConsensusParams(0, 1), false},
+		{newConsensusParams(0, 0), false},
+		{newConsensusParams(0, 10), false},
+		{newConsensusParams(10, -1), false},
+		{newConsensusParams(47*1024*1024, 400), true},
+		{newConsensusParams(10, 400), true},
+		{newConsensusParams(100*1024*1024, 400), true},
+		{newConsensusParams(101*1024*1024, 400), false},
+		{newConsensusParams(1024*1024*1024, 400), false},
+	}
+	for _, testCase := range testCases {
+		if testCase.valid {
+			assert.NoError(t, testCase.params.Validate(), "expected no error for valid params")
+		} else {
+			assert.Error(t, testCase.params.Validate(), "expected error for non valid params")
+		}
+	}
+}