diff --git a/app/assets/javascripts/admin/addon/components/watched-word-form.js b/app/assets/javascripts/admin/addon/components/watched-word-form.js
index 0902e0b3e4d..e00032f22c1 100644
--- a/app/assets/javascripts/admin/addon/components/watched-word-form.js
+++ b/app/assets/javascripts/admin/addon/components/watched-word-form.js
@@ -47,9 +47,12 @@ export default Component.extend({
     const filtered = words.filter(
       (content) => content.action === this.actionKey
     );
-    return filtered.every(
-      (content) => content.word.toLowerCase() !== word.toLowerCase()
-    );
+    return filtered.every((content) => {
+      if (content.case_sensitive === true) {
+        return content.word !== word;
+      }
+      return content.word.toLowerCase() !== word.toLowerCase();
+    });
   },
 
   actions: {
diff --git a/app/assets/javascripts/discourse/tests/acceptance/admin-watched-words-test.js b/app/assets/javascripts/discourse/tests/acceptance/admin-watched-words-test.js
index 52aff93232a..e2d6b667024 100644
--- a/app/assets/javascripts/discourse/tests/acceptance/admin-watched-words-test.js
+++ b/app/assets/javascripts/discourse/tests/acceptance/admin-watched-words-test.js
@@ -86,6 +86,14 @@ acceptance("Admin - Watched Words", function (needs) {
     assert
       .dom(".watched-words-list .watched-word")
       .hasText(`Discourse ${I18n.t("admin.watched_words.case_sensitive")}`);
+
+    fillIn(".watched-word-form input", "discourse");
+    click(".case-sensitivity-checkbox");
+    await click(".watched-word-form button");
+
+    assert
+      .dom(".watched-words-list .watched-word")
+      .hasText(`discourse ${I18n.t("admin.watched_words.case_sensitive")}`);
   });
 
   test("remove words", async function (assert) {
diff --git a/app/models/watched_word.rb b/app/models/watched_word.rb
index 66cee4588ad..e396544e87d 100644
--- a/app/models/watched_word.rb
+++ b/app/models/watched_word.rb
@@ -40,6 +40,9 @@ class WatchedWord < ActiveRecord::Base
   after_destroy :clear_cache
 
   scope :by_action, -> { order("action ASC, word ASC") }
+  scope :for, ->(word:) do
+    where("(word ILIKE :word AND case_sensitive = 'f') OR (word LIKE :word AND case_sensitive = 't')", word: word)
+  end
 
   def self.normalize_word(w)
     w.strip.squeeze('*')
@@ -61,7 +64,7 @@ class WatchedWord < ActiveRecord::Base
 
   def self.create_or_update_word(params)
     new_word = normalize_word(params[:word])
-    w = WatchedWord.where("word ILIKE ?", new_word).first || WatchedWord.new(word: new_word)
+    w = self.for(word: new_word).first_or_initialize(word: new_word)
     w.replacement = params[:replacement] if params[:replacement]
     w.action_key = params[:action_key] if params[:action_key]
     w.action = params[:action] if params[:action]
diff --git a/spec/models/watched_word_spec.rb b/spec/models/watched_word_spec.rb
index cf3ab22618d..ef593d29f2a 100644
--- a/spec/models/watched_word_spec.rb
+++ b/spec/models/watched_word_spec.rb
@@ -125,5 +125,36 @@ RSpec.describe WatchedWord do
       expect(updated.case_sensitive?).to eq(false)
     end
 
+    context "when a case-sensitive word already exists" do
+      subject(:create_or_update) do
+        described_class.create_or_update_word(word: word, action_key: :block, case_sensitive: true)
+      end
+
+      fab!(:existing_word) { Fabricate(:watched_word, case_sensitive: true, word: "Meta") }
+
+      context "when providing the exact same word" do
+        let(:word) { existing_word.word }
+
+        it "doesn't create a new watched word" do
+          expect { create_or_update }.not_to change { described_class.count }
+        end
+
+        it "returns the existing watched word" do
+          expect(create_or_update).to eq(existing_word)
+        end
+      end
+
+      context "when providing the same word with a different case" do
+        let(:word) { "metA" }
+
+        it "creates a new watched word" do
+          expect(create_or_update).not_to eq(existing_word)
+        end
+
+        it "returns the new watched word" do
+          expect(create_or_update).to have_attributes word: "metA", case_sensitive: true, action: 1
+        end
+      end
+    end
   end
 end