diff --git a/src/action.rs b/src/action.rs
index 693dd1c5..c56462f7 100644
--- a/src/action.rs
+++ b/src/action.rs
@@ -17,6 +17,7 @@ pub enum Modifier {
     /// so it's simple to implement as levels are deprecated in squeekboard.
     Control,
     Alt,
+    Mod4,
 }
 
 /// Action to perform on the keypress and, in reverse, on keyrelease
diff --git a/src/data.rs b/src/data.rs
index e559c515..ecc63fe4 100644
--- a/src/data.rs
+++ b/src/data.rs
@@ -658,6 +658,9 @@ fn create_action<H: logging::Handler>(
             Modifier::Alt => action::Action::ApplyModifier(
                 action::Modifier::Alt,
             ),
+            Modifier::Mod4 => action::Action::ApplyModifier(
+                action::Modifier::Mod4,
+            ),
             unsupported_modifier => {
                 warning_handler.handle(
                     logging::Level::Bug,
diff --git a/src/submission.rs b/src/submission.rs
index ba9f0c7a..e2230718 100644
--- a/src/submission.rs
+++ b/src/submission.rs
@@ -270,6 +270,7 @@ impl Submission {
             .map(|(_id, m)| match m {
                 Modifier::Control => Modifiers::CONTROL,
                 Modifier::Alt => Modifiers::MOD1,
+                Modifier::Mod4 => Modifiers::MOD4,
             })
             .fold(Modifiers::empty(), |m, n| m | n);
         self.virtual_keyboard.set_modifiers_state(raw_modifiers);