diff --git a/x/distribution/types/fee_pool_test.go b/x/distribution/types/fee_pool_test.go
index ebf5bc4b0..de774ca3c 100644
--- a/x/distribution/types/fee_pool_test.go
+++ b/x/distribution/types/fee_pool_test.go
@@ -1,4 +1,4 @@
-package types
+package types_test
 
 import (
 	"testing"
@@ -6,14 +6,14 @@ import (
 	"github.com/stretchr/testify/require"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/distribution/types"
 )
 
 func TestValidateGenesis(t *testing.T) {
 
-	fp := InitialFeePool()
+	fp := types.InitialFeePool()
 	require.Nil(t, fp.ValidateGenesis())
 
-	fp2 := FeePool{CommunityPool: sdk.DecCoins{{Denom: "stake", Amount: sdk.NewDec(-1)}}}
+	fp2 := types.FeePool{CommunityPool: sdk.DecCoins{{Denom: "stake", Amount: sdk.NewDec(-1)}}}
 	require.NotNil(t, fp2.ValidateGenesis())
-
 }
diff --git a/x/distribution/types/params.go b/x/distribution/types/params.go
index ecd04ece6..212b0b99f 100644
--- a/x/distribution/types/params.go
+++ b/x/distribution/types/params.go
@@ -51,7 +51,7 @@ func (p *Params) ParamSetPairs() paramtypes.ParamSetPairs {
 func (p Params) ValidateBasic() error {
 	if p.CommunityTax.IsNegative() || p.CommunityTax.GT(sdk.OneDec()) {
 		return fmt.Errorf(
-			"community tax should non-negative and less than one: %s", p.CommunityTax,
+			"community tax should be non-negative and less than one: %s", p.CommunityTax,
 		)
 	}
 	if p.BaseProposerReward.IsNegative() {
@@ -64,9 +64,9 @@ func (p Params) ValidateBasic() error {
 			"bonus proposer reward should be positive: %s", p.BonusProposerReward,
 		)
 	}
-	if v := p.BaseProposerReward.Add(p.BonusProposerReward); v.GT(sdk.OneDec()) {
+	if v := p.BaseProposerReward.Add(p.BonusProposerReward).Add(p.CommunityTax); v.GT(sdk.OneDec()) {
 		return fmt.Errorf(
-			"sum of base and bonus proposer reward cannot greater than one: %s", v,
+			"sum of base, bonus proposer rewards, and community tax cannot be greater than one: %s", v,
 		)
 	}
 
diff --git a/x/distribution/types/params_internal_test.go b/x/distribution/types/params_internal_test.go
new file mode 100644
index 000000000..f132df9d5
--- /dev/null
+++ b/x/distribution/types/params_internal_test.go
@@ -0,0 +1,34 @@
+package types
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+)
+
+func Test_validateAuxFuncs(t *testing.T) {
+	type args struct {
+		i interface{}
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantErr bool
+	}{
+		{"wrong type", args{10.5}, true},
+		{"empty sdk.Dec", args{sdk.Dec{}}, true},
+		{"negative", args{sdk.NewDec(-1)}, true},
+		{"one dec", args{sdk.NewDec(1)}, false},
+		{"two dec", args{sdk.NewDec(2)}, true},
+	}
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.wantErr, validateCommunityTax(tt.args.i) != nil)
+			require.Equal(t, tt.wantErr, validateBaseProposerReward(tt.args.i) != nil)
+			require.Equal(t, tt.wantErr, validateBonusProposerReward(tt.args.i) != nil)
+		})
+	}
+}
diff --git a/x/distribution/types/params_test.go b/x/distribution/types/params_test.go
index cf2501604..d156df728 100644
--- a/x/distribution/types/params_test.go
+++ b/x/distribution/types/params_test.go
@@ -1,4 +1,4 @@
-package types
+package types_test
 
 import (
 	"testing"
@@ -6,29 +6,44 @@ import (
 	"github.com/stretchr/testify/require"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/x/distribution/types"
 )
 
-func Test_validateAuxFuncs(t *testing.T) {
-	type args struct {
-		i interface{}
+func TestParams_ValidateBasic(t *testing.T) {
+	toDec := sdk.MustNewDecFromStr
+
+	type fields struct {
+		CommunityTax        sdk.Dec
+		BaseProposerReward  sdk.Dec
+		BonusProposerReward sdk.Dec
+		WithdrawAddrEnabled bool
 	}
 	tests := []struct {
 		name    string
-		args    args
+		fields  fields
 		wantErr bool
 	}{
-		{"wrong type", args{10.5}, true},
-		{"nil Int pointer", args{sdk.Dec{}}, true},
-		{"negative", args{sdk.NewDec(-1)}, true},
-		{"one dec", args{sdk.NewDec(1)}, false},
-		{"two dec", args{sdk.NewDec(2)}, true},
+		{"success", fields{toDec("0.1"), toDec("0.5"), toDec("0.4"), false}, false},
+		{"negative community tax", fields{toDec("-0.1"), toDec("0.5"), toDec("0.4"), false}, true},
+		{"negative base proposer reward", fields{toDec("0.1"), toDec("-0.5"), toDec("0.4"), false}, true},
+		{"negative bonus proposer reward", fields{toDec("0.1"), toDec("0.5"), toDec("-0.4"), false}, true},
+		{"total sum greater than 1", fields{toDec("0.2"), toDec("0.5"), toDec("0.4"), false}, true},
 	}
 	for _, tt := range tests {
-		tt := tt
 		t.Run(tt.name, func(t *testing.T) {
-			require.Equal(t, tt.wantErr, validateCommunityTax(tt.args.i) != nil)
-			require.Equal(t, tt.wantErr, validateBaseProposerReward(tt.args.i) != nil)
-			require.Equal(t, tt.wantErr, validateBonusProposerReward(tt.args.i) != nil)
+			p := types.Params{
+				CommunityTax:        tt.fields.CommunityTax,
+				BaseProposerReward:  tt.fields.BaseProposerReward,
+				BonusProposerReward: tt.fields.BonusProposerReward,
+				WithdrawAddrEnabled: tt.fields.WithdrawAddrEnabled,
+			}
+			if err := p.ValidateBasic(); (err != nil) != tt.wantErr {
+				t.Errorf("ValidateBasic() error = %v, wantErr %v", err, tt.wantErr)
+			}
 		})
 	}
 }
+
+func TestDefaultParams(t *testing.T) {
+	require.NoError(t, types.DefaultParams().ValidateBasic())
+}