diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 579ce3dc4..891f13c8a 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -2,8 +2,11 @@ name: Build
 on: [pull_request]
 jobs:
   build-mac:
-    name: Build Mac UI
-    runs-on: macos-latest
+    name: Mac UI on ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest]
+    runs-on: ${{ matrix.os }}
     steps:
     - name: Checkout
       uses: actions/checkout@v4
@@ -11,15 +14,38 @@ jobs:
       working-directory: OSBindings/Mac
       run: xcodebuild CODE_SIGN_IDENTITY=-
   build-sdl:
-    name: Build SDL UI
-    runs-on: ubuntu-latest
+    name: SDL UI on ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-latest, ubuntu-latest]
+    runs-on: ${{ matrix.os }}
     steps:
     - name: Checkout
       uses: actions/checkout@v4
     - name: Install dependencies
+      shell: bash
       run: |
-        sudo apt-get --allow-releaseinfo-change update
-        sudo apt-get --fix-missing install gcc-10 libsdl2-dev scons
+        case $RUNNER_OS in
+          Linux)
+            sudo apt-get --allow-releaseinfo-change update
+            sudo apt-get --fix-missing install gcc-10 libsdl2-dev scons
+            ;;
+          macOS)
+            brew install scons sdl2
+            ;;
+        esac
     - name: Make
       working-directory: OSBindings/SDL
-      run: scons -j$(nproc --all)
+      shell: bash
+      run: |
+        case $RUNNER_OS in
+          Linux)
+            jobs=$(nproc --all)
+            ;;
+          macOS)
+            jobs=$(sysctl -n hw.activecpu)
+            ;;
+          *)
+            jobs=1
+        esac
+        scons -j"$jobs"
diff --git a/Machines/Apple/AppleII/Video.hpp b/Machines/Apple/AppleII/Video.hpp
index f29ba1a3a..ae3478928 100644
--- a/Machines/Apple/AppleII/Video.hpp
+++ b/Machines/Apple/AppleII/Video.hpp
@@ -472,9 +472,9 @@ template <class BusHandler, bool is_iie> class Video: public VideoBase {
 							// Supply the real phase value if this is an Apple build.
 							// TODO: eliminate UGLY HACK.
 #if defined(__APPLE__) && !defined(IGNORE_APPLE)
-							constexpr int phase = 224;
+							constexpr uint8_t phase = 224;
 #else
-							constexpr int phase = 0;
+							constexpr uint8_t phase = 192;
 #endif
 
 							crt_.output_colour_burst((colour_burst_end - colour_burst_start) * 14, phase);
diff --git a/OSBindings/SDL/SConstruct b/OSBindings/SDL/SConstruct
index f8c614a18..02f9893b1 100644
--- a/OSBindings/SDL/SConstruct
+++ b/OSBindings/SDL/SConstruct
@@ -1,4 +1,5 @@
 import glob
+import os
 import sys
 
 # Establish UTF-8 encoding for Python 2.
@@ -7,7 +8,7 @@ if sys.version_info < (3, 0):
 	sys.setdefaultencoding('utf-8')
 
 # Create build environment.
-env = Environment()
+env = Environment(ENV = {'PATH' : os.environ['PATH']})
 
 # Determine compiler and linker flags for SDL.
 env.ParseConfig('sdl2-config --cflags')
@@ -139,7 +140,14 @@ SOURCES += glob.glob('../../Storage/Tape/Parsers/*.cpp')
 env.Append(CCFLAGS = ['--std=c++17', '--std=c++1z', '-Wall', '-O2', '-DNDEBUG'])
 
 # Add additional libraries to link against.
-env.Append(LIBS = ['libz', 'pthread', 'GL'])
+env.Append(LIBS = ['libz', 'pthread'])
+
+# Add additional platform-specific compiler flags, libraries, and frameworks.
+if env['PLATFORM'] == 'darwin':
+	env.Append(CCFLAGS = ['-DGL_SILENCE_DEPRECATION', '-DIGNORE_APPLE'])
+	env.Append(FRAMEWORKS = ['Accelerate', 'OpenGL'])
+else:
+	env.Append(LIBS = ['GL'])
 
 # Build target.
 env.Program(target = 'clksignal', source = SOURCES)
diff --git a/OSBindings/SDL/main.cpp b/OSBindings/SDL/main.cpp
index 226cb7c41..d0c253d30 100644
--- a/OSBindings/SDL/main.cpp
+++ b/OSBindings/SDL/main.cpp
@@ -19,7 +19,7 @@
 #include <memory>
 #include <sys/stat.h>
 
-#include <SDL2/SDL.h>
+#include <SDL.h>
 
 #include "../../Analyser/Static/StaticAnalyser.hpp"
 #include "../../Machines/Utility/MachineForTarget.hpp"