diff --git a/README.md b/README.md
index a0f82910..466609c4 100644
--- a/README.md
+++ b/README.md
@@ -77,7 +77,9 @@ properties (see below).
 
 * `Key_mouseScrollUp`, `Key_mouseScrollDn`: Scroll the mouse wheel up or down,
   respectively.
-
+* `Key_mouseScrollL`, `Key_mouseScrollR`: Scroll the mouse wheel left or right,
+  respectively.
+  
 ### Buttons
 
 Buttons are even simpler than movement: there is no movement speed, nor
diff --git a/src/Kaleidoscope-MouseKeys.cpp b/src/Kaleidoscope-MouseKeys.cpp
index a417f667..4455dde4 100644
--- a/src/Kaleidoscope-MouseKeys.cpp
+++ b/src/Kaleidoscope-MouseKeys.cpp
@@ -29,6 +29,10 @@ void MouseKeys_::scrollWheel(uint8_t keyCode) {
     kaleidoscope::hid::moveMouse(0, 0, wheelSpeed);
   else if (keyCode & KEY_MOUSE_DOWN)
     kaleidoscope::hid::moveMouse(0, 0, -wheelSpeed);
+  else if (keyCode & KEY_MOUSE_LEFT)
+    kaleidoscope::hid::moveMouse(0, 0, 0, -wheelSpeed);
+  else if (keyCode & KEY_MOUSE_RIGHT)
+    kaleidoscope::hid::moveMouse(0, 0, 0, wheelSpeed);
 }
 
 void MouseKeys_::loopHook(bool postClear) {
diff --git a/src/MouseKeyDefs.h b/src/MouseKeyDefs.h
index 9f5bdbc9..2a10af25 100644
--- a/src/MouseKeyDefs.h
+++ b/src/MouseKeyDefs.h
@@ -36,8 +36,8 @@
 #define Key_mouseDnR      (Key) { KEY_MOUSE_DOWN | KEY_MOUSE_RIGHT, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
 #define Key_mouseScrollUp (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_UP, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
 #define Key_mouseScrollDn (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_DOWN, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
-#define Key_mouseScrollL
-#define Key_mouseScrollR
+#define Key_mouseScrollL  (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_LEFT, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
+#define Key_mouseScrollR  (Key) { KEY_MOUSE_WHEEL | KEY_MOUSE_RIGHT, KEY_FLAGS|SYNTHETIC|IS_MOUSE_KEY }
 #define Key_mouseBtnL     (Key) { KEY_MOUSE_BUTTON | KEY_MOUSE_BTN_L, KEY_FLAGS | SYNTHETIC | IS_MOUSE_KEY }
 #define Key_mouseBtnM     (Key) { KEY_MOUSE_BUTTON | KEY_MOUSE_BTN_M, KEY_FLAGS | SYNTHETIC | IS_MOUSE_KEY }
 #define Key_mouseBtnR     (Key) { KEY_MOUSE_BUTTON | KEY_MOUSE_BTN_R, KEY_FLAGS | SYNTHETIC | IS_MOUSE_KEY }