diff --git a/input.go b/input.go
index 5387eac7d..93a7cd500 100644
--- a/input.go
+++ b/input.go
@@ -335,7 +335,10 @@ func IsStandardGamepadLayoutAvailable(id GamepadID) bool {
 //
 // UpdateStandardGamepadLayoutMappings works atomically. If an error happens, nothing is updated.
 func UpdateStandardGamepadLayoutMappings(mappings string) (bool, error) {
-	return gamepaddb.Update([]byte(mappings))
+	if err := gamepaddb.Update([]byte(mappings)); err != nil {
+		return false, err
+	}
+	return true, nil
 }
 
 // TouchID represents a touch's identifier.
diff --git a/internal/gamepaddb/gamepaddb.go b/internal/gamepaddb/gamepaddb.go
index 547c0b01b..38705d81a 100644
--- a/internal/gamepaddb/gamepaddb.go
+++ b/internal/gamepaddb/gamepaddb.go
@@ -92,10 +92,10 @@ var additionalGLFWGamepads = []byte(`
 `)
 
 func init() {
-	if _, err := Update(gamecontrollerdbTxt); err != nil {
+	if err := Update(gamecontrollerdbTxt); err != nil {
 		panic(err)
 	}
-	if _, err := Update(additionalGLFWGamepads); err != nil {
+	if err := Update(additionalGLFWGamepads); err != nil {
 		panic(err)
 	}
 }
@@ -139,11 +139,18 @@ func parseLine(line string, platform platform) (id string, name string, buttons
 		return "", "", nil, nil, nil
 	}
 	tokens := strings.Split(line, ",")
+	if len(tokens) < 2 {
+		return "", "", nil, nil, fmt.Errorf("gamepaddb: syntax error")
+	}
+
 	for _, token := range tokens[2:] {
 		if len(token) == 0 {
 			continue
 		}
 		tks := strings.Split(token, ":")
+		if len(tks) < 2 {
+			return "", "", nil, nil, fmt.Errorf("gamepaddb: syntax error")
+		}
 
 		// Note that the platform part is listed in the definition of SDL_GetPlatform.
 		if tks[0] == "platform" {
@@ -501,7 +508,7 @@ func IsButtonPressed(id string, button StandardButton, state GamepadState) bool
 // The string must be in the format of SDL_GameControllerDB.
 //
 // Update works atomically. If an error happens, nothing is updated.
-func Update(mappingData []byte) (bool, error) {
+func Update(mappingData []byte) error {
 	mappingsM.Lock()
 	defer mappingsM.Unlock()
 
@@ -519,11 +526,11 @@ func Update(mappingData []byte) (bool, error) {
 	for {
 		line, err := r.ReadString('\n')
 		if err != nil && err != io.EOF {
-			return false, err
+			return err
 		}
 		id, name, buttons, axes, err1 := parseLine(line, currentPlatform)
 		if err1 != nil {
-			return false, err1
+			return err1
 		}
 		if id != "" {
 			lines = append(lines, parsedLine{
@@ -544,7 +551,7 @@ func Update(mappingData []byte) (bool, error) {
 		gamepadAxisMappings[l.id] = l.axes
 	}
 
-	return true, nil
+	return nil
 }
 
 func addAndroidDefaultMappings(id string) bool {
diff --git a/internal/gamepaddb/gamepaddb_test.go b/internal/gamepaddb/gamepaddb_test.go
new file mode 100644
index 000000000..42f2149cb
--- /dev/null
+++ b/internal/gamepaddb/gamepaddb_test.go
@@ -0,0 +1,67 @@
+// Copyright 2022 The Ebitengine Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gamepaddb_test
+
+import (
+	"testing"
+
+	"github.com/hajimehoshi/ebiten/v2/internal/gamepaddb"
+)
+
+func TestUpdate(t *testing.T) {
+	cases := []struct {
+		Input string
+		Err   bool
+	}{
+		{
+			Input: "",
+			Err:   false,
+		},
+		{
+			Input: "{}",
+			Err:   true,
+		},
+		{
+			Input: "00000000000000000000000000000000",
+			Err:   true,
+		},
+		{
+			Input: "00000000000000000000000000000000,foo",
+			Err:   false,
+		},
+		{
+			Input: "00000000000000000000000000000000,foo,platform",
+			Err:   true,
+		},
+		{
+			Input: "00000000000000000000000000000000,foo,pltform:Foo",
+			Err:   true,
+		},
+		{
+			Input: "00000000000000000000000000000000,foo,platform:Windows",
+			Err:   false,
+		},
+	}
+
+	for _, c := range cases {
+		err := gamepaddb.Update([]byte(c.Input))
+		if err == nil && c.Err {
+			t.Errorf("Update(%q) should return an error but not", c.Input)
+		}
+		if err != nil && !c.Err {
+			t.Errorf("Update(%q) should not return an error but returned %v", c.Input, err)
+		}
+	}
+}