diff --git a/src/typescript/Scala.tmLanguage.ts b/src/typescript/Scala.tmLanguage.ts
index 80870a0..08b22b1 100644
--- a/src/typescript/Scala.tmLanguage.ts
+++ b/src/typescript/Scala.tmLanguage.ts
@@ -150,6 +150,9 @@ export const scalaTmLanguage: TmLanguage = {
         {
           include: '#inheritance'
         },
+        {
+          include: '#extension'
+        },
         {
           include: '#imports'
         },
@@ -859,6 +862,32 @@ export const scalaTmLanguage: TmLanguage = {
         }
       ]
     },
+    extension: {
+      patterns: [
+        {
+          match: `(extension)\\s+(?:(${plainid})\\s)?\\s*(on|(?=\\{))`,
+          captures: {
+            '1': {
+              name: 'keyword.declaration.scala'
+            },
+            '2': {
+              name: 'entity.name.class'
+            },
+            '3': {
+              name: 'keyword.declaration.scala'
+            }
+          }
+        },
+        {
+          match: `(extension)\\s+(?=[\\[\\(])`,
+          captures: {
+            '1': {
+              name: 'keyword.declaration.scala'
+            },
+          }
+        }
+      ]
+    },
     'parameter-list': {
       patterns: [
         {
diff --git a/tests/unit/extension-on.test.scala b/tests/unit/extension-on.test.scala
new file mode 100644
index 0000000..ef1dfa9
--- /dev/null
+++ b/tests/unit/extension-on.test.scala
@@ -0,0 +1,23 @@
+// SYNTAX TEST "source.scala"
+
+    extension on (x: Rational):
+//  ^^^^^^^^^ keyword.declaration.scala
+//            ^^ keyword.declaration.scala
+//                ^ variable.parameter.scala
+//                   ^^^^^^^^ entity.name.class
+       def > (y: Rational): Boolean = y < x
+
+   extension Ops on (x: Rational):
+// ^^^^^^^^^ keyword.declaration.scala
+//           ^^^ entity.name.class
+//               ^^ keyword.declaration.scala
+//                   ^ variable.parameter.scala
+//                      ^^^^^^^^ entity.name.class
+      def > (y: Rational): Boolean = y < x
+
+   extension stringOps {  }
+// ^^^^^^^^^ keyword.declaration.scala
+//           ^^^^^^^^^ entity.name.class
+
+   extension {  }
+// ^^^^^^^^^ keyword.declaration.scala
diff --git a/tests/unit/extension.test.scala b/tests/unit/extension.test.scala
new file mode 100644
index 0000000..27685c8
--- /dev/null
+++ b/tests/unit/extension.test.scala
@@ -0,0 +1,19 @@
+// SYNTAX TEST "source.scala"
+
+    extension (x: T) def combine (y: T): T
+//  ^^^^^^^^^ keyword.declaration.scala
+//             ^ variable.parameter.scala
+//              ^ meta.colon.scala
+//                ^ entity.name.class
+//                   ^^^ keyword.declaration.scala
+//                       ^^^^^^^ entity.name.function.declaration
+
+
+    extension [T](x: T) def combine (y: T): T
+//  ^^^^^^^^^ keyword.declaration.scala
+//             ^ entity.name.class
+//                ^ variable.parameter.scala
+//                 ^ meta.colon.scala
+//                   ^ entity.name.class
+//                      ^^^ keyword.declaration.scala
+//                          ^^^^^^^ entity.name.function.declaration