diff --git a/plugins/common/common.go b/plugins/common/common.go
index d6833bae2..227c18b50 100644
--- a/plugins/common/common.go
+++ b/plugins/common/common.go
@@ -931,18 +931,18 @@ func IsValidAppName(appName string) error {
 	return errors.New("App name must begin with lowercase alphanumeric character, and may only contain lowercase alphanumerics, dots, and hyphens")
 }
 
-// isValidAppNameOld verifies that the app name matches the old naming restrictions
-func isValidAppNameOld(appName string) error {
+// IsValidAppNameOld verifies that the app name matches the old naming restrictions
+func IsValidAppNameOld(appName string) error {
 	if appName == "" {
 		return errors.New("Please specify an app to run the command on")
 	}
 
-	r, _ := regexp.Compile("^[a-z0-9][a-z0-9.-]*$")
+	r, _ := regexp.Compile("^[a-z0-9][a-z0-9._-]*$")
 	if r.MatchString(appName) {
 		return nil
 	}
 
-	return errors.New("App name must begin with lowercase alphanumeric character, and may only contain lowercase alphanumerics, dots, and hyphens")
+	return errors.New("App name must begin with lowercase alphanumeric character, and may only contain lowercase alphanumerics, dots, hyphens, and underscores")
 }
 
 // AppDoesNotExist wraps error to include the app name
@@ -981,7 +981,7 @@ func VarArgs(arguments []string, skip int) []string {
 // naming conventions exists
 func VerifyAppName(appName string) error {
 	newErr := IsValidAppName(appName)
-	oldErr := isValidAppNameOld(appName)
+	oldErr := IsValidAppNameOld(appName)
 	if newErr != nil && oldErr != nil {
 		return newErr
 	}
diff --git a/plugins/common/common_test.go b/plugins/common/common_test.go
index 14c0ef032..0123a6c56 100644
--- a/plugins/common/common_test.go
+++ b/plugins/common/common_test.go
@@ -94,6 +94,36 @@ func TestCommonIsValidAppName(t *testing.T) {
 	}
 }
 
+func TestCommonIsValidAppNameOld(t *testing.T) {
+	RegisterTestingT(t)
+	validNames := []string{
+		"myapp",
+		"my-app",
+		"my.app",
+		"my_app",
+		"legacy_app_name",
+		"app_v2",
+	}
+	for _, name := range validNames {
+		Expect(IsValidAppNameOld(name)).To(Succeed(), "expected %q to be a valid app name", name)
+	}
+
+	invalidNames := []string{
+		"app;id",
+		"app$cmd",
+		"app|cat",
+		"app/cmd",
+		"app:cmd",
+		"App",
+		"-app",
+		"_app",
+		"",
+	}
+	for _, name := range invalidNames {
+		Expect(IsValidAppNameOld(name)).To(HaveOccurred(), "expected %q to be rejected", name)
+	}
+}
+
 func TestCommonIsValidAppNameRejectsShellMetacharacters(t *testing.T) {
 	RegisterTestingT(t)
 	invalidNames := []string{
diff --git a/plugins/common/functions b/plugins/common/functions
index 2d9877810..c933c4791 100755
--- a/plugins/common/functions
+++ b/plugins/common/functions
@@ -222,22 +222,14 @@ fn-is-valid-app-name() {
   declare desc="verify that the app name matches naming restrictions"
   local APP="$1"
   [[ -z "$APP" ]] && dokku_log_fail "Please specify an app to run the command on"
-  if [[ "$APP" =~ ^[a-z0-9][a-z0-9.-]*$ ]]; then
-    return 0
-  fi
-
-  return 1
+  "$PLUGIN_CORE_AVAILABLE_PATH/common/common" --quiet is-valid-app-name "$APP"
 }
 
 fn-is-valid-app-name-old() {
   declare desc="verify that the app name matches the old naming restrictions"
   local APP="$1"
   [[ -z "$APP" ]] && dokku_log_fail "Please specify an app to run the command on"
-  if [[ "$APP" =~ ^[a-z0-9][a-z0-9.-]*$ ]]; then
-    return 0
-  fi
-
-  return 1
+  "$PLUGIN_CORE_AVAILABLE_PATH/common/common" --quiet is-valid-app-name-old "$APP"
 }
 
 fn-plugn-trigger-exists() {
diff --git a/plugins/common/src/common/common.go b/plugins/common/src/common/common.go
index 5c95746aa..58412f591 100644
--- a/plugins/common/src/common/common.go
+++ b/plugins/common/src/common/common.go
@@ -86,6 +86,12 @@ func main() {
 		} else {
 			fmt.Print("false")
 		}
+	case "is-valid-app-name":
+		appName := flag.Arg(1)
+		err = common.IsValidAppName(appName)
+	case "is-valid-app-name-old":
+		appName := flag.Arg(1)
+		err = common.IsValidAppNameOld(appName)
 	case "verify-app-name":
 		appName := flag.Arg(1)
 		err = common.VerifyAppName(appName)