diff --git a/router/middleware.go b/router/middleware.go
index f9a141663..5b202e262 100644
--- a/router/middleware.go
+++ b/router/middleware.go
@@ -264,6 +264,10 @@ func (h *Handlers) ValidatePinID() echo.MiddlewareFunc {
 				}
 			}
 
+			if pin.Message.ID == uuid.Nil {
+				return c.NoContent(http.StatusNotFound)
+			}
+
 			if ok, err := h.Repo.IsChannelAccessibleToUser(userID, pin.Message.ChannelID); err != nil {
 				c.Logger().Error(err)
 				return c.NoContent(http.StatusInternalServerError)
diff --git a/router/pin_test.go b/router/pin_test.go
index 342710621..115cb5f03 100644
--- a/router/pin_test.go
+++ b/router/pin_test.go
@@ -1,6 +1,7 @@
 package router
 
 import (
+	"github.com/satori/go.uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/traPtitech/traQ/repository"
@@ -61,6 +62,29 @@ func TestHandlers_GetPin(t *testing.T) {
 			Status(http.StatusUnauthorized)
 	})
 
+	t.Run("Not found", func(t *testing.T) {
+		t.Parallel()
+		e := makeExp(t, server)
+		e.GET("/api/1.0/pins/{pinID}", uuid.NewV4()).
+			WithCookie(sessions.CookieName, session).
+			Expect().
+			Status(http.StatusNotFound)
+	})
+
+	t.Run("Not found (deleted message)", func(t *testing.T) {
+		t.Parallel()
+
+		message := mustMakeMessage(t, repo, testUser.ID, channel.ID)
+		pin := mustMakePin(t, repo, message.ID, testUser.ID)
+		require.NoError(t, repo.DeleteMessage(message.ID))
+
+		e := makeExp(t, server)
+		e.GET("/api/1.0/pins/{pinID}", pin).
+			WithCookie(sessions.CookieName, session).
+			Expect().
+			Status(http.StatusNotFound)
+	})
+
 	t.Run("Successful1", func(t *testing.T) {
 		t.Parallel()
 		e := makeExp(t, server)
@@ -74,6 +98,7 @@ func TestHandlers_GetPin(t *testing.T) {
 			String().
 			Equal(pin.String())
 	})
+
 }
 
 func TestHandlers_DeletePin(t *testing.T) {
diff --git a/utils/imagemagick/imagemagick.go b/utils/imagemagick/imagemagick.go
index bb4f89ed1..4ffad4649 100644
--- a/utils/imagemagick/imagemagick.go
+++ b/utils/imagemagick/imagemagick.go
@@ -58,7 +58,7 @@ func ResizeAnimationGIF(ctx context.Context, execPath string, src io.Reader, max
 	if !expand {
 		sizer += ">"
 	}
-	cmd := exec.CommandContext(ctx, execPath, "-coalesce", "-resize", sizer, "-deconstruct", "-", "gif:-")
+	cmd := exec.CommandContext(ctx, execPath, "-", "-coalesce", "-repage", "0x0", "-resize", sizer, "-layers", "Optimize", "gif:-")
 
 	b, err := cmdPipe(cmd, src)
 	if err != nil {