diff --git a/libs/core/_locales/core-jsdoc-strings.json b/libs/core/_locales/core-jsdoc-strings.json
index 8d01f01c..0e7542c8 100644
--- a/libs/core/_locales/core-jsdoc-strings.json
+++ b/libs/core/_locales/core-jsdoc-strings.json
@@ -538,6 +538,7 @@
   "pins.C12": "Pin C12",
   "pins.C16": "Pin C16",
   "pins.C17": "Pin C17",
+  "pins.C18": "Pin C18",
   "pins.C4": "Pin C4",
   "pins.C5": "Pin C5",
   "pins.C6": "Pin C6",
diff --git a/libs/core/enums.d.ts b/libs/core/enums.d.ts
index 92887109..3d71529d 100644
--- a/libs/core/enums.d.ts
+++ b/libs/core/enums.d.ts
@@ -464,6 +464,7 @@ declare namespace motors {
     C12 = 106,  // MICROBIT_ID_IO_P6
     C16 = 102,  // MICROBIT_ID_IO_P2
     C17 = 108,  // MICROBIT_ID_IO_P8
+    C18 = 120,  // MICROBIT_ID_IO_P20
     }
 
 
diff --git a/libs/core/pins.cpp b/libs/core/pins.cpp
index 07784bab..fb773036 100644
--- a/libs/core/pins.cpp
+++ b/libs/core/pins.cpp
@@ -15,7 +15,8 @@ enum class DigitalPin {
     C11 = MICROBIT_ID_IO_P7,   // LED matrix C8
     C12 = MICROBIT_ID_IO_P6,   // LED matrix C9
     C16 = MICROBIT_ID_IO_P2,   // RX
-    C17 = MICROBIT_ID_IO_P8   // TX
+    C17 = MICROBIT_ID_IO_P8,   // TX
+    C18 = MICROBIT_ID_IO_P20  // SDA
 };
 
 enum class AnalogPin {
diff --git a/libs/core/pinscompat.ts b/libs/core/pinscompat.ts
index 5e79a0a2..3e50da8e 100644
--- a/libs/core/pinscompat.ts
+++ b/libs/core/pinscompat.ts
@@ -213,4 +213,10 @@ namespace pins {
     //% fixedInstance whenUsed
     export const C17: AnalogInPin = new MicrobitPin(DigitalPin.C17);
     
+    /**
+     * Pin C18
+     */
+    //% fixedInstance whenUsed
+    export const C18: DigitalInOutPin = new MicrobitPin(DigitalPin.C18);
+    
 }
\ No newline at end of file