diff --git a/new/button_windows.c b/new/button_windows.c
index c331e89..c57b778 100644
--- a/new/button_windows.c
+++ b/new/button_windows.c
@@ -6,11 +6,11 @@ struct button {
 	void *onClickedData;
 };
 
-static BOOL onWM_COMMAND(uiControl *c, WPARAM wParam, LPARAM lParam, LRESULT *lResult)
+static BOOL onWM_COMMAND(uiControl *c, WORD code, LRESULT *lResult)
 {
 	struct button *b = (struct button *) (c->data);
 
-	if (HIWORD(wParam) != BN_CLICKED)
+	if (code != BN_CLICKED)
 		return FALSE;
 	(*(b->onClicked))(c, b->onClickedData);
 	*lResult = 0;
diff --git a/new/checkbox_windows.c b/new/checkbox_windows.c
index 55699a6..abe128d 100644
--- a/new/checkbox_windows.c
+++ b/new/checkbox_windows.c
@@ -6,13 +6,13 @@ struct checkbox {
 	void *onToggledData;
 };
 
-static BOOL onWM_COMMAND(uiControl *c, WPARAM wParam, LPARAM lParam, LRESULT *lResult)
+static BOOL onWM_COMMAND(uiControl *c, WORD code, LRESULT *lResult)
 {
 	struct checkbox *cc = (struct checkbox *) (c->data);
 	HWND hwnd;
 	WPARAM check;
 
-	if (HIWORD(wParam) != BN_CLICKED)
+	if (code != BN_CLICKED)
 		return FALSE;
 
 	// we didn't use BS_AUTOCHECKBOX (see controls_windows.go) so we have to manage the check state ourselves
diff --git a/new/entry_windows.c b/new/entry_windows.c
index f8521b4..df4a91d 100644
--- a/new/entry_windows.c
+++ b/new/entry_windows.c
@@ -4,7 +4,7 @@
 struct entry {
 };
 
-static BOOL onWM_COMMAND(uiControl *c, WPARAM wParam, LPARAM lParam, LRESULT *lResult)
+static BOOL onWM_COMMAND(uiControl *c, WORD code, LRESULT *lResult)
 {
 	return FALSE;
 }
diff --git a/new/newcontrol_windows.c b/new/newcontrol_windows.c
index d2f4508..f95f67f 100644
--- a/new/newcontrol_windows.c
+++ b/new/newcontrol_windows.c
@@ -5,7 +5,7 @@ typedef struct singleHWND singleHWND;
 
 struct singleHWND {
 	HWND hwnd;
-	BOOL (*onWM_COMMAND)(uiControl *, WPARAM, LPARAM, LRESULT *);
+	BOOL (*onWM_COMMAND)(uiControl *, WORD, LRESULT *);
 	BOOL (*onWM_NOTIFY)(uiControl *, WPARAM, LPARAM, LRESULT *);
 	void (*onWM_DESTROY)(uiControl *);
 	uintptr_t parent;
@@ -65,7 +65,7 @@ static LRESULT CALLBACK singleSubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam,
 
 	switch (uMsg) {
 	case msgCOMMAND:
-		if ((*(s->onWM_COMMAND))(c, wParam, lParam, &lResult) != FALSE)
+		if ((*(s->onWM_COMMAND))(c, HIWORD(wParam), &lResult) != FALSE)
 			return lResult;
 		break;
 	case msgNOTIFY:
diff --git a/new/ui_windows.h b/new/ui_windows.h
index 4ade067..b89af3a 100644
--- a/new/ui_windows.h
+++ b/new/ui_windows.h
@@ -23,7 +23,7 @@ struct uiWindowsNewControlParams {
 	// Store the result in *lResult and return any non-FALSE value (such as TRUE) to return the given result; return FALSE to pass the notification up to your window procedure.
 	// Note that these are only issued if they come from the uiControl itself; notifications from children of the uiControl (such as a header control) will be received normally.
 	// TODO don't give WPARAM/LPARAM raw
-	BOOL (*onWM_COMMAND)(uiControl *c, WPARAM wParam, LPARAM lParam, LRESULT *lResult);
+	BOOL (*onWM_COMMAND)(uiControl *c, WORD code, LRESULT *lResult);
 	BOOL (*onWM_NOTIFY)(uiControl *c, WPARAM wParam, LPARAM lParam, LRESULT *lResult);
 	// This is called in WM_DESTROY.
 	void (*onWM_DESTROY)(uiControl *c);