diff --git a/ui/cocoa/cocoa.go b/ui/cocoa/cocoa.go
index 0cc6b1e83..93f104fe1 100644
--- a/ui/cocoa/cocoa.go
+++ b/ui/cocoa/cocoa.go
@@ -7,7 +7,9 @@ package cocoa
 // #include "input.h"
 //
 // void StartApplication(void);
-// void* CreateWindow(size_t width, size_t height, const char* title);
+// void* CreateGLContext(void* sharedGLContext);
+// void SetCurrentGLContext(void* glContext);
+// void* CreateWindow(size_t width, size_t height, const char* title, void* glContext);
 // void PollEvents(void);
 // void BeginDrawing(void* window);
 // void EndDrawing(void* window);
@@ -77,14 +79,17 @@ func New(screenWidth, screenHeight, screenScale int, title string) *UI {
 
 	C.StartApplication()
 
-	ui.window = C.CreateWindow(C.size_t(ui.screenWidth * ui.screenScale),
-		C.size_t(ui.screenHeight * ui.screenScale),
-		cTitle)
+	context := C.CreateGLContext(unsafe.Pointer(nil))
+	C.SetCurrentGLContext(context);
 	ui.graphicsDevice = opengl.NewDevice(
 		ui.screenWidth,
 		ui.screenHeight,
 		ui.screenScale)
 
+	ui.window = C.CreateWindow(C.size_t(ui.screenWidth * ui.screenScale),
+		C.size_t(ui.screenHeight * ui.screenScale),
+		cTitle,
+		context)
 	currentUI = ui
 	return ui
 }
diff --git a/ui/cocoa/mainloop.c b/ui/cocoa/mainloop.c
index 120c4ed68..b85854e15 100644
--- a/ui/cocoa/mainloop.c
+++ b/ui/cocoa/mainloop.c
@@ -15,7 +15,7 @@ void StartApplication() {
   [app activateIgnoringOtherApps:YES];
 }
 
-void* CreateGLContext() {
+void* CreateGLContext(void* sharedGLContext) {
   NSOpenGLPixelFormatAttribute attributes[] = {
     NSOpenGLPFAWindow,
     NSOpenGLPFADoubleBuffer,
@@ -25,24 +25,27 @@ void* CreateGLContext() {
   };
   NSOpenGLPixelFormat* format = [[NSOpenGLPixelFormat alloc]
                                   initWithAttributes:attributes];
-  NSOpenGLContext* glContext = [[NSOpenGLContext alloc] initWithFormat:format
-                                                          shareContext:nil];
+  NSOpenGLContext* glContext =
+    [[NSOpenGLContext alloc] initWithFormat:format
+                               shareContext:(NSOpenGLContext*)sharedGLContext];
   [format release];
   return glContext;
 }
 
-void* CreateWindow(size_t width, size_t height, const char* title) {
-  NSOpenGLContext* glContext = CreateGLContext();
-  [glContext makeCurrentContext];
+void SetCurrentGLContext(void* glContext) {
+  [(NSOpenGLContext*)glContext makeCurrentContext];
+}
 
+// This takes the ownership of glContext.
+void* CreateWindow(size_t width, size_t height, const char* title, void* glContext) {
   NSSize size = NSMakeSize(width, height);
   EbitenWindow* window = [[EbitenWindow alloc]
                             initWithSize:size
-                               glContext:glContext];
+                               glContext:(NSOpenGLContext*)glContext];
   [window setTitle: [[NSString alloc] initWithUTF8String:title]];
   [window makeKeyAndOrderFront:nil];
 
-  [glContext setView:[window contentView]];
+  [(NSOpenGLContext*)glContext setView:[window contentView]];
 
   return window;
 }
@@ -61,6 +64,7 @@ void PollEvents(void) {
 }
 
 void BeginDrawing(void* window) {
+  [[(EbitenWindow*)window glContext] makeCurrentContext];
   glClear(GL_COLOR_BUFFER_BIT);
 }