diff --git a/models/user/user.go b/models/user/user.go
index fb43f01696..a0ee1e81b4 100644
--- a/models/user/user.go
+++ b/models/user/user.go
@@ -576,7 +576,7 @@ func GetUserSalt() (string, error) {
 // Note: The set of characters here can safely expand without a breaking change,
 // but characters removed from this set can cause user account linking to break
 var (
-	customCharsReplacement    = strings.NewReplacer("Æ", "AE")
+	customCharsReplacement    = strings.NewReplacer("Æ", "AE", "ß", "ss")
 	removeCharsRE             = regexp.MustCompile(`['´\x60]`)
 	removeDiacriticsTransform = transform.Chain(norm.NFD, runes.Remove(runes.In(unicode.Mn)), norm.NFC)
 	replaceCharsHyphenRE      = regexp.MustCompile(`[\s~+]`)
diff --git a/models/user/user_test.go b/models/user/user_test.go
index 63a12b788f..7c89337510 100644
--- a/models/user/user_test.go
+++ b/models/user/user_test.go
@@ -633,6 +633,7 @@ func Test_NormalizeUserFromEmail(t *testing.T) {
 		{"test", "test", true},
 		{"Sinéad.O'Connor", "Sinead.OConnor", true},
 		{"Æsir", "AEsir", true},
+		{"Flußpferd", "Flusspferd", true},
 		// \u00e9\u0065\u0301
 		{"éé", "ee", true},
 		{"Awareness Hub", "Awareness-Hub", true},