diff --git a/bool_test.go b/bool_test.go
index 714b37a..eb9cb01 100644
--- a/bool_test.go
+++ b/bool_test.go
@@ -46,6 +46,13 @@ func TestUnmarshalBool(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullBool(t, null, "null json")
+
+	var badType Bool
+	err = json.Unmarshal(intJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullBool(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalBool(t *testing.T) {
diff --git a/float_test.go b/float_test.go
index 9eeae01..a4ba3a4 100644
--- a/float_test.go
+++ b/float_test.go
@@ -45,6 +45,13 @@ func TestUnmarshalFloat(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullFloat(t, null, "null json")
+
+	var badType Float
+	err = json.Unmarshal(boolJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullFloat(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalFloat(t *testing.T) {
diff --git a/gin-bin b/gin-bin
deleted file mode 100644
index 0ef32d9..0000000
Binary files a/gin-bin and /dev/null differ
diff --git a/int_test.go b/int_test.go
index 8fe2e26..708b89f 100644
--- a/int_test.go
+++ b/int_test.go
@@ -45,6 +45,13 @@ func TestUnmarshalInt(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullInt(t, null, "null json")
+
+	var badType Int
+	err = json.Unmarshal(boolJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullInt(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalInt(t *testing.T) {
diff --git a/string_test.go b/string_test.go
index 88c484f..3a444d8 100644
--- a/string_test.go
+++ b/string_test.go
@@ -56,6 +56,13 @@ func TestUnmarshalString(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullStr(t, null, "null json")
+
+	var badType String
+	err = json.Unmarshal(boolJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullStr(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalString(t *testing.T) {
diff --git a/zero/bool.go b/zero/bool.go
index e1b5153..e59cf96 100644
--- a/zero/bool.go
+++ b/zero/bool.go
@@ -4,6 +4,8 @@ import (
 	"database/sql"
 	"encoding/json"
 	"errors"
+	"fmt"
+	"reflect"
 )
 
 // Bool is a nullable bool.
@@ -49,6 +51,8 @@ func (b *Bool) UnmarshalJSON(data []byte) error {
 	case nil:
 		b.Valid = false
 		return nil
+	default:
+		err = fmt.Errorf("json: cannot unmarshal %v into Go value of type zero.Bool", reflect.TypeOf(v).Name())
 	}
 	b.Valid = (err == nil) && b.Bool
 	return err
diff --git a/zero/bool_test.go b/zero/bool_test.go
index 348f651..28f508c 100644
--- a/zero/bool_test.go
+++ b/zero/bool_test.go
@@ -59,6 +59,13 @@ func TestUnmarshalBool(t *testing.T) {
 		panic("err should not be nil")
 	}
 	assertNullBool(t, invalid, "invalid json")
+
+	var badType Bool
+	err = json.Unmarshal(intJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullBool(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalBool(t *testing.T) {
diff --git a/zero/float.go b/zero/float.go
index 8b36be1..247ea08 100644
--- a/zero/float.go
+++ b/zero/float.go
@@ -3,6 +3,8 @@ package zero
 import (
 	"database/sql"
 	"encoding/json"
+	"fmt"
+	"reflect"
 	"strconv"
 )
 
@@ -50,6 +52,8 @@ func (f *Float) UnmarshalJSON(data []byte) error {
 	case nil:
 		f.Valid = false
 		return nil
+	default:
+		err = fmt.Errorf("json: cannot unmarshal %v into Go value of type zero.Float", reflect.TypeOf(v).Name())
 	}
 	f.Valid = (err == nil) && (f.Float64 != 0)
 	return err
diff --git a/zero/float_test.go b/zero/float_test.go
index cd4fd2f..d3d44f6 100644
--- a/zero/float_test.go
+++ b/zero/float_test.go
@@ -50,6 +50,13 @@ func TestUnmarshalFloat(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullFloat(t, null, "null json")
+
+	var badType Float
+	err = json.Unmarshal(boolJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullFloat(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalFloat(t *testing.T) {
diff --git a/zero/int.go b/zero/int.go
index 9efb7bc..df79d0a 100644
--- a/zero/int.go
+++ b/zero/int.go
@@ -3,6 +3,8 @@ package zero
 import (
 	"database/sql"
 	"encoding/json"
+	"fmt"
+	"reflect"
 	"strconv"
 )
 
@@ -51,6 +53,8 @@ func (i *Int) UnmarshalJSON(data []byte) error {
 	case nil:
 		i.Valid = false
 		return nil
+	default:
+		err = fmt.Errorf("json: cannot unmarshal %v into Go value of type zero.Int", reflect.TypeOf(v).Name())
 	}
 	i.Valid = (err == nil) && (i.Int64 != 0)
 	return err
diff --git a/zero/int_test.go b/zero/int_test.go
index 7007fbe..2910b6a 100644
--- a/zero/int_test.go
+++ b/zero/int_test.go
@@ -51,6 +51,13 @@ func TestUnmarshalInt(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullInt(t, null, "null json")
+
+	var badType Int
+	err = json.Unmarshal(boolJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullInt(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalInt(t *testing.T) {
diff --git a/zero/string.go b/zero/string.go
index 3472153..a1aae5a 100644
--- a/zero/string.go
+++ b/zero/string.go
@@ -7,6 +7,8 @@ package zero
 import (
 	"database/sql"
 	"encoding/json"
+	"fmt"
+	"reflect"
 )
 
 // String is a nullable string.
@@ -53,6 +55,8 @@ func (s *String) UnmarshalJSON(data []byte) error {
 	case nil:
 		s.Valid = false
 		return nil
+	default:
+		err = fmt.Errorf("json: cannot unmarshal %v into Go value of type zero.String", reflect.TypeOf(v).Name())
 	}
 	s.Valid = (err == nil) && (s.String != "")
 	return err
diff --git a/zero/string_test.go b/zero/string_test.go
index 8995b35..5e6385d 100644
--- a/zero/string_test.go
+++ b/zero/string_test.go
@@ -44,6 +44,13 @@ func TestUnmarshalString(t *testing.T) {
 	err = json.Unmarshal(nullJSON, &null)
 	maybePanic(err)
 	assertNullStr(t, null, "null json")
+
+	var badType String
+	err = json.Unmarshal(boolJSON, &badType)
+	if err == nil {
+		panic("err should not be nil")
+	}
+	assertNullStr(t, badType, "wrong type json")
 }
 
 func TestTextUnmarshalString(t *testing.T) {