diff --git a/app/services/discourse_translator/discourse_ai.rb b/app/services/discourse_translator/discourse_ai.rb
index 93dc4be3..47426f3d 100644
--- a/app/services/discourse_translator/discourse_ai.rb
+++ b/app/services/discourse_translator/discourse_ai.rb
@@ -6,8 +6,9 @@
 module DiscourseTranslator
   class DiscourseAi < Base
     MAX_DETECT_LOCALE_TEXT_LENGTH = 1000
-    def self.language_supported?(_)
-      true
+    def self.language_supported?(detected_lang)
+      locale_without_region = I18n.locale.to_s.split("_").first
+      detected_lang != locale_without_region
     end
 
     def self.detect(topic_or_post)
diff --git a/lib/discourse_translator/guardian_extension.rb b/lib/discourse_translator/guardian_extension.rb
index f508d20e..1380651c 100644
--- a/lib/discourse_translator/guardian_extension.rb
+++ b/lib/discourse_translator/guardian_extension.rb
@@ -18,4 +18,21 @@ def can_detect_language?(post)
         post&.user&.in_any_groups?(SiteSetting.restrict_translation_by_poster_group_map)
     ) && post.raw.present? && post.post_type != Post.types[:small_action]
   end
+
+  def can_translate?(post)
+    return false if !user_group_allow_translate?
+
+    # we will deal with regionalized_strings (not syms) when comparing locales
+    # e.g. "en_GB"
+    #      not "en-GB"
+    #      nor :en_GB (I18n.locale)
+    detected_lang =
+      post.custom_fields[::DiscourseTranslator::DETECTED_LANG_CUSTOM_FIELD].to_s.sub("-", "_")
+    return false if detected_lang.blank?
+
+    detected_lang != I18n.locale.to_s &&
+      "DiscourseTranslator::#{SiteSetting.translator}".constantize.language_supported?(
+        detected_lang,
+      )
+  end
 end
diff --git a/plugin.rb b/plugin.rb
index ffca1837..06b49f8a 100644
--- a/plugin.rb
+++ b/plugin.rb
@@ -44,14 +44,6 @@ module ::DiscourseTranslator
   end
 
   add_to_serializer :post, :can_translate do
-    return false if !scope.user_group_allow_translate?
-
-    detected_lang = post_custom_fields[::DiscourseTranslator::DETECTED_LANG_CUSTOM_FIELD]
-    return false if detected_lang.blank?
-
-    detected_lang.to_sym != I18n.locale &&
-      "DiscourseTranslator::#{SiteSetting.translator}".constantize.language_supported?(
-        detected_lang,
-      )
+    scope.can_translate?(object)
   end
 end
diff --git a/spec/lib/guardian_extension_spec.rb b/spec/lib/guardian_extension_spec.rb
index 2a83216f..c9ac4b48 100644
--- a/spec/lib/guardian_extension_spec.rb
+++ b/spec/lib/guardian_extension_spec.rb
@@ -113,4 +113,64 @@
       end
     end
   end
+
+  describe "#can_translate?" do
+    fab!(:group)
+    fab!(:user) { Fabricate(:user, locale: "en", groups: [group]) }
+    fab!(:post)
+
+    let(:guardian) { Guardian.new(user) }
+
+    it "returns false when translator disabled" do
+      SiteSetting.translator_enabled = false
+
+      expect(guardian.can_translate?(post)).to eq(false)
+    end
+
+    describe "when translator enabled" do
+      before { SiteSetting.translator_enabled = true }
+
+      describe "anon user" do
+        before { SiteSetting.restrict_translation_by_group = "#{Group::AUTO_GROUPS[:everyone]}" }
+
+        it "cannot translate" do
+          expect(Guardian.new.can_translate?(post)).to eq(false)
+        end
+      end
+
+      describe "logged in user" do
+        it "cannot translate when user is not in restrict_translation_by_group" do
+          SiteSetting.restrict_translation_by_group = "#{group.id + 1}"
+
+          expect(guardian.can_translate?(post)).to eq(false)
+        end
+
+        describe "user is in restrict_translation_by_group" do
+          before { SiteSetting.restrict_translation_by_group = "#{group.id}" }
+
+          describe "locale is :xx" do
+            before { I18n.stubs(:locale).returns(:pt) }
+
+            it "cannot translate when post does not have DETECTED_LANG_CUSTOM_FIELD" do
+              expect(guardian.can_translate?(post)).to eq(false)
+            end
+
+            it "cannot translate when post has DETECTED_LANG_CUSTOM_FIELD matches locale" do
+              post.custom_fields[DiscourseTranslator::DETECTED_LANG_CUSTOM_FIELD] = "pt"
+              post.save
+
+              expect(guardian.can_translate?(post)).to eq(false)
+            end
+
+            it "can translate when post has DETECTED_LANG_CUSTOM_FIELD does not match locale" do
+              post.custom_fields[DiscourseTranslator::DETECTED_LANG_CUSTOM_FIELD] = "jp"
+              post.save
+
+              expect(guardian.can_translate?(post)).to eq(true)
+            end
+          end
+        end
+      end
+    end
+  end
 end
diff --git a/spec/services/discourse_ai_spec.rb b/spec/services/discourse_ai_spec.rb
index 37bcefc2..c7cf1188 100644
--- a/spec/services/discourse_ai_spec.rb
+++ b/spec/services/discourse_ai_spec.rb
@@ -15,9 +15,15 @@
   end
 
   describe ".language_supported?" do
-    it "returns true for any language" do
+    it "returns true when detected language is different from i18n locale" do
+      I18n.stubs(:locale).returns(:xx)
       expect(described_class.language_supported?("any-language")).to eq(true)
     end
+
+    it "returns false when detected language is same base language as i18n locale" do
+      I18n.stubs(:locale).returns(:en_GB)
+      expect(described_class.language_supported?("en")).to eq(false)
+    end
   end
 
   describe ".detect" do