diff --git a/internal/uidriver/glfw/ui.go b/internal/uidriver/glfw/ui.go
index fd0247b83..dc326ae43 100644
--- a/internal/uidriver/glfw/ui.go
+++ b/internal/uidriver/glfw/ui.go
@@ -910,10 +910,13 @@ func (u *UserInterface) update() (float64, float64, bool, error) {
 	// Calling this inside setWindowSize didn't work (#1363).
 	if !u.vsyncInited {
 		u.vsync = u.isInitVsyncEnabled()
-		u.updateVsync()
 		u.vsyncInited = true
 	}
 
+	// Call updateVsync regardless of vsyncInited.
+	// When toggling to fullscreen, vsync state might be reset unexpectedly (#1787).
+	u.updateVsync()
+
 	outsideWidth, outsideHeight, outsideSizeChanged := u.updateSize()
 
 	// TODO: Updating the input can be skipped when clock.Update returns 0 (#1367).