diff --git a/Libraries/LibWeb/WebGL/WebGL2RenderingContextBase.idl b/Libraries/LibWeb/WebGL/WebGL2RenderingContextBase.idl
index 037f5d92fce..379ec7212a5 100644
--- a/Libraries/LibWeb/WebGL/WebGL2RenderingContextBase.idl
+++ b/Libraries/LibWeb/WebGL/WebGL2RenderingContextBase.idl
@@ -399,7 +399,7 @@ interface mixin WebGL2RenderingContextBase {
     WebGLSync? fenceSync(GLenum condition, GLbitfield flags);
     [FIXME] GLboolean isSync(WebGLSync? sync); // [WebGLHandlesContextLoss]
     [FIXME] undefined deleteSync(WebGLSync? sync);
-    [FIXME] GLenum clientWaitSync(WebGLSync sync, GLbitfield flags, GLuint64 timeout);
+    GLenum clientWaitSync(WebGLSync sync, GLbitfield flags, GLuint64 timeout);
     [FIXME] undefined waitSync(WebGLSync sync, GLbitfield flags, GLint64 timeout);
     [FIXME] any getSyncParameter(WebGLSync sync, GLenum pname);
 
diff --git a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWebGLRenderingContext.cpp b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWebGLRenderingContext.cpp
index c60babea153..8188c93f4e0 100644
--- a/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWebGLRenderingContext.cpp
+++ b/Meta/Lagom/Tools/CodeGenerators/LibWeb/GenerateWebGLRenderingContext.cpp
@@ -948,6 +948,11 @@ public:
                 gl_call_arguments.append(ByteString::formatted("{} ? {}->handle() : 0", parameter_name, parameter_name));
                 continue;
             }
+            if (parameter.type->name() == "WebGLSync"sv) {
+                // FIXME: Remove the GLsync cast once sync_handle actually returns the proper GLsync type.
+                gl_call_arguments.append(ByteString::formatted("(GLsync)({} ? {}->sync_handle() : nullptr)", parameter_name, parameter_name));
+                continue;
+            }
             if (parameter.type->name() == "BufferSource"sv) {
                 function_impl_generator.set("buffer_source_name", parameter_name);
                 function_impl_generator.append(R"~~~(