diff --git a/lib/discourse_tagging.rb b/lib/discourse_tagging.rb
index 2c0519cd199..ac2061b41f9 100644
--- a/lib/discourse_tagging.rb
+++ b/lib/discourse_tagging.rb
@@ -202,10 +202,13 @@ module DiscourseTagging
   end
 
   def self.clean_tag(tag)
+    tag = tag.dup
     tag.downcase! if SiteSetting.force_lowercase_tags
-    tag.strip
-      .gsub(/\s+/, '-').squeeze('-')
-      .gsub(TAGS_FILTER_REGEXP, '')[0...SiteSetting.max_tag_length]
+    tag.strip!
+    tag.gsub!(/\s+/, '-')
+    tag.squeeze!('-')
+    tag.gsub!(TAGS_FILTER_REGEXP, '')
+    tag[0...SiteSetting.max_tag_length]
   end
 
   def self.tags_for_saving(tags_arg, guardian, opts = {})
diff --git a/spec/components/discourse_tagging_spec.rb b/spec/components/discourse_tagging_spec.rb
index 5d52375406b..f080a03f8cb 100644
--- a/spec/components/discourse_tagging_spec.rb
+++ b/spec/components/discourse_tagging_spec.rb
@@ -209,7 +209,8 @@ describe DiscourseTagging do
 
     describe "clean_tag" do
       it "downcases new tags if setting enabled" do
-        expect(DiscourseTagging.clean_tag("HeLlO")).to eq("hello")
+        expect(DiscourseTagging.clean_tag("HeLlO".freeze)).to eq("hello")
+
         SiteSetting.force_lowercase_tags = false
         expect(DiscourseTagging.clean_tag("HeLlO")).to eq("HeLlO")
       end