diff --git a/content_script.js b/content_script.js
index b174a6a..f389b1a 100644
--- a/content_script.js
+++ b/content_script.js
@@ -1,7 +1,7 @@
 DEACTIVATE_KEY = 'deactivate-this-extension-pls-interactive-fics-yalla-bina';
 
 chrome.runtime.onMessage.addListener((message, sender, sendResponse) => {
-	escapeAndReplace(message.input_word, message.replace_value)
+	escapeAndReplace(message.input_word, message.replace_value, message.case_sensitive)
 });
 
 const replaceAll = () => {
@@ -11,17 +11,18 @@ const replaceAll = () => {
 				if (key == 'person') {
 					const regexp_y_n = /\by\/n\b|\(y\/n\)|\[y\/n\]/ig
 					replace(regexp_y_n, items[key])
-				} else if (key !== DEACTIVATE_KEY) {
-					escapeAndReplace(key, items[key])
+				} else if (key !== DEACTIVATE_KEY && !key.endsWith('_case_sensitive')) {
+					escapeAndReplace(key, items[key], items[`${key}_case_sensitive`])
 				}
 			}
 		}
 	})
 }
 
-const escapeAndReplace = (input_word, replace_value) => {
+const escapeAndReplace = (input_word, replace_value, case_sensitive) => {
 	const input_word_escaped = escapeRegExp(input_word.trim())
-	const regexp_input_word = new RegExp(`\\b${input_word_escaped}\\b`, "ig")
+	const flags = case_sensitive ? "g" : "ig"
+	const regexp_input_word = new RegExp(`\\b${input_word_escaped}\\b`, flags)
 	replace(regexp_input_word, replace_value)
 }
 
diff --git a/popup.css b/popup.css
index c044727..2a5bd9f 100644
--- a/popup.css
+++ b/popup.css
@@ -21,10 +21,10 @@ label *:not([type="checkbox"]){
 }
 
 .other-words input:not([type="checkbox"]){
-	margin-top:0.2em;
+	margin-top:0.5em;
 	width:100%;
 }
-.other-words .other, .other-words .replaceBy{
+.other-words .other, .other-words .replace-with{
 	width:98%;
 }
 .other-words .change{
diff --git a/popup.html b/popup.html
index ba7e88e..a5ba1da 100644
--- a/popup.html
+++ b/popup.html
@@ -24,11 +24,15 @@
 						<span>Value (e.g. L/N, E/C, etc):</span>
 						<input type="text" id="replace-word" class="other"/>
 					</label>
-					<br>
+					<label>
+						<input type="checkbox" id="is-case-sensitive">Case sensitive
+					</label>
+					<br><br>
 					<label>
 						<span>Replace with:</span>
-						<input type="text" id="replace-with" class="replaceBy"/>
+						<input type="text" id="replace-with" class="replace-with"/>
 					</label>
+					<br>
 					<label>
 						<input type="checkbox" id="is-perm">Store this replacement
 					</label>
diff --git a/popup.js b/popup.js
index 110d4f6..d3d348f 100644
--- a/popup.js
+++ b/popup.js
@@ -27,10 +27,12 @@ const clearName = () => {
 const replaceOther = () => {
 	const input_word = document.getElementById('replace-word').value
 	const replacement = document.getElementById('replace-with').value
+	const is_case_sensitive = document.getElementById('is-case-sensitive').checked
 	if (input_word && replacement) {
 		if (document.getElementById('is-perm').checked) {
 			const obj = {}
 			obj[input_word] = replacement
+			obj[`${input_word}_case_sensitive`] = is_case_sensitive
 			chrome.storage.local.set(obj)
 		}
 
@@ -39,7 +41,8 @@ const replaceOther = () => {
 				tabs[0].id,
 				{
 					input_word: input_word,
-					replace_value: replacement
+					replace_value: replacement,
+					case_sensitive: is_case_sensitive
 				})
 		})
 	}