diff --git a/.github/workflows/linux.yml b/.github/workflows/linux.yml
index 48ecca0..b8f61ca 100644
--- a/.github/workflows/linux.yml
+++ b/.github/workflows/linux.yml
@@ -24,7 +24,6 @@ jobs:
             libx11-dev \
             libxi-dev \
             libxcursor-dev \
-            qt5-default \
             qtbase5-dev
 
       - name: Configure CMake
diff --git a/qt/src/qsplot_widget.cpp b/qt/src/qsplot_widget.cpp
index 56c1522..cd48ef3 100644
--- a/qt/src/qsplot_widget.cpp
+++ b/qt/src/qsplot_widget.cpp
@@ -238,7 +238,7 @@ void QSplotWidget::paintGL() {
     const int fbWidth = static_cast<int>(width() * dpr);
     const int fbHeight = static_cast<int>(height() * dpr);
 
-    // Begin pass with Qt's default framebuffer
+    // Begin pass with Qt's framebuffer (NOT 0 - QOpenGLWidget has its own FBO)
     sg_pass_action pass_action{};
     pass_action.colors[0].load_action = SG_LOADACTION_CLEAR;
     pass_action.colors[0].clear_value = {impl_->bgR, impl_->bgG, impl_->bgB, impl_->bgA};
@@ -250,6 +250,8 @@ void QSplotWidget::paintGL() {
     pass.swapchain.sample_count = 1;
     pass.swapchain.color_format = SG_PIXELFORMAT_RGBA8;
     pass.swapchain.depth_format = SG_PIXELFORMAT_DEPTH_STENCIL;
+    // CRITICAL: QOpenGLWidget uses its own FBO, not the default (0)
+    pass.swapchain.gl.framebuffer = defaultFramebufferObject();
     sg_begin_pass(pass);
 
     // Call the render callback if set
diff --git a/src/plot_exporter.cpp b/src/plot_exporter.cpp
index 161f63f..b0de817 100644
--- a/src/plot_exporter.cpp
+++ b/src/plot_exporter.cpp
@@ -263,6 +263,10 @@ struct PlotExporter::Impl {
 
         return true;
 #else
+        // Silence unused parameter warnings for non-GL backends
+        (void)filename;
+        (void)is_jpeg;
+        (void)quality;
         std::fprintf(stderr, "PlotExporter: Not implemented for this graphics backend\n");
         return false;
 #endif
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index bef5d02..3fd2fde 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -62,6 +62,11 @@ add_executable(test_tick_label_formatter test_tick_label_formatter.cpp)
 target_link_libraries(test_tick_label_formatter PRIVATE GTest::gtest_main splot)
 gtest_discover_tests(test_tick_label_formatter)
 
+# On macOS, sokol_impl_stub.cpp needs to be compiled as Objective-C++ for Metal backend
+if(APPLE)
+    set_source_files_properties(sokol_impl_stub.cpp PROPERTIES LANGUAGE OBJCXX)
+endif()
+
 # PlotLegend tests (requires Sokol implementation stub for linking)
 add_executable(test_plot_legend test_plot_legend.cpp sokol_impl_stub.cpp)
 target_link_libraries(test_plot_legend PRIVATE GTest::gtest_main splot ${SOKOL_PLATFORM_LIBS})