diff --git a/src/cmd/devdraw/x11-memdraw.h b/src/cmd/devdraw/x11-memdraw.h
index 0c78b9b6..4238f06e 100644
--- a/src/cmd/devdraw/x11-memdraw.h
+++ b/src/cmd/devdraw/x11-memdraw.h
@@ -67,6 +67,7 @@ struct Xprivate {
 	int		kbuttons;
 	int		kstate;
 	int		altdown;
+	int		button1map;	/* logical button that physical button 1 maps to */
 
 	Xwin*	windows;
 };
diff --git a/src/cmd/devdraw/x11-screen.c b/src/cmd/devdraw/x11-screen.c
index f46a2788..74c89975 100644
--- a/src/cmd/devdraw/x11-screen.c
+++ b/src/cmd/devdraw/x11-screen.c
@@ -408,9 +408,20 @@ runxevent(XEvent *xev)
 				be->button = 2;
 			else if(_x.kstate & Mod1Mask)
 				be->button = 3;
+			_x.button1map = be->button;
 		}
 		// fall through
 	case ButtonRelease:
+		/*
+		 * X reports the physical button on release, but ButtonPress
+		 * may have remapped button 1 to 2 or 3 (via Ctrl or Alt).
+		 * Use the same mapping so we clear the correct bit.
+		 */
+		if(xev->type == ButtonRelease) {
+			be = (XButtonEvent*)xev;
+			if(be->button == 1 && _x.button1map != 0)
+				be->button = _x.button1map;
+		}
 		_x.altdown = 0;
 		// fall through
 	case MotionNotify: