diff --git a/src/Window.c b/src/Window.c
index 9e5f2c731..466e46d5b 100644
--- a/src/Window.c
+++ b/src/Window.c
@@ -4722,6 +4722,8 @@ void GLContext_Create(void) {
 	attribs.antialias = false;
 
 	ctx_handle = emscripten_webgl_create_context("#canvas", &attribs);
+	if (!ctx_handle) Window_ShowDialog("WebGL unsupported", "WebGL is required to run ClassiCube");
+
 	emscripten_webgl_make_context_current(ctx_handle);
 	emscripten_set_webglcontextlost_callback("#canvas", NULL, 0, GLContext_OnLost);
 }