diff --git a/internal/regexes/regexes.go b/internal/regexes/regexes.go
index 25fcfc03a..aca502345 100644
--- a/internal/regexes/regexes.go
+++ b/internal/regexes/regexes.go
@@ -47,6 +47,7 @@
 	mentionFinder            = `(?:^|\s)(@` + usernameGrp + `+(?:@` + domainGrp + `+)?)` // Extract all mentions from a text, each mention may include domain.
 	emojiShortcode           = `\w{2,30}`                                                // Pattern for emoji shortcodes. maximumEmojiShortcodeLength = 30
 	emojiFinder              = `(?:\b)?:(` + emojiShortcode + `):(?:\b)?`                // Extract all emoji shortcodes from a text.
+	emojiValidator           = `^` + emojiShortcode + `$`                                // Validate a single emoji shortcode.
 	usernameStrict           = `^[a-z0-9_]{1,64}$`                                       // Pattern for usernames on THIS instance. maximumUsernameLength = 64
 	usernameRelaxed          = `[a-z0-9_\.]{1,}`                                         // Relaxed version of username that can match instance accounts too.
 	misskeyReportNotesFinder = `(?m)(?:^Note: ((?:http|https):\/\/.*)$)`                 // Extract reported Note URIs from the text of a Misskey report/flag.
@@ -95,8 +96,8 @@
 	// MentionFinder extracts whole mentions from a piece of text.
 	MentionFinder = regexp.MustCompile(mentionFinder)
 
-	// EmojiShortcode validates an emoji name.
-	EmojiShortcode = regexp.MustCompile(emojiShortcode)
+	// EmojiValidator validates an emoji shortcode.
+	EmojiValidator = regexp.MustCompile(emojiValidator)
 
 	// EmojiFinder extracts emoji strings from a piece of text.
 	// See: https://regex101.com/r/478XGM/1
diff --git a/internal/validate/formvalidation.go b/internal/validate/formvalidation.go
index 1b5996b4b..3d1d05072 100644
--- a/internal/validate/formvalidation.go
+++ b/internal/validate/formvalidation.go
@@ -191,7 +191,7 @@ func CustomCSS(customCSS string) error {
 // for emoji shortcodes, to figure out whether it's a valid shortcode, ie., 2-30 characters,
 // a-zA-Z, numbers, and underscores.
 func EmojiShortcode(shortcode string) error {
-	if !regexes.EmojiShortcode.MatchString(shortcode) {
+	if !regexes.EmojiValidator.MatchString(shortcode) {
 		return fmt.Errorf("shortcode %s did not pass validation, must be between 2 and 30 characters, letters, numbers, and underscores only", shortcode)
 	}
 	return nil
diff --git a/internal/validate/formvalidation_test.go b/internal/validate/formvalidation_test.go
index 40830407c..578b300ea 100644
--- a/internal/validate/formvalidation_test.go
+++ b/internal/validate/formvalidation_test.go
@@ -321,6 +321,63 @@ func (suite *ValidationTestSuite) TestValidateCustomCSSTooLongUnicode() {
 	suite.EqualError(err, "custom_css must be less than 5 characters, but submitted custom_css was 10 characters")
 }
 
+func (suite *ValidationTestSuite) TestValidateEmojiShortcode() {
+	type testStruct struct {
+		shortcode string
+		ok        bool
+	}
+
+	for _, test := range []testStruct{
+		{
+			shortcode: "peepee",
+			ok:        true,
+		},
+		{
+			shortcode: "poo-poo",
+			ok:        false,
+		},
+		{
+			shortcode: "-peepee",
+			ok:        false,
+		},
+		{
+			shortcode: "p",
+			ok:        false,
+		},
+		{
+			shortcode: "pp",
+			ok:        true,
+		},
+		{
+			shortcode: "6969",
+			ok:        true,
+		},
+		{
+			shortcode: "__peepee",
+			ok:        true,
+		},
+		{
+			shortcode: "_",
+			ok:        false,
+		},
+		{
+			// Too long.
+			shortcode: "_XxX_Ultimate_Gamer_dude_6969_420_",
+			ok:        false,
+		},
+		{
+			shortcode: "_XxX_Ultimate_Gamer_dude_6969_",
+			ok:        true,
+		},
+	} {
+		err := validate.EmojiShortcode(test.shortcode)
+		ok := err == nil
+		if !suite.Equal(test.ok, ok) {
+			suite.T().Logf("fail on %s", test.shortcode)
+		}
+	}
+}
+
 func TestValidationTestSuite(t *testing.T) {
 	suite.Run(t, new(ValidationTestSuite))
 }