diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm b/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm
index 292be240d..31f82e7aa 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm	
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/CSScanTarget.mm	
@@ -20,6 +20,8 @@ struct Uniforms {
 	float aspectRatioMultiplier;
 	simd::float3x3 toRGB;
 	simd::float3x3 fromRGB;
+	float zoom;
+	simd::float2 offset;
 };
 
 constexpr size_t NumBufferedScans = 2048;
@@ -186,7 +188,20 @@ using BufferingScanTarget = Outputs::Display::BufferingScanTarget;
 }
 
 - (void)setAspectRatio {
-	uniforms()->aspectRatioMultiplier = float(_scanTarget.modals().aspect_ratio / (_view.bounds.size.width / _view.bounds.size.height));
+	const auto modals = _scanTarget.modals();
+	const auto viewAspectRatio = (_view.bounds.size.width / _view.bounds.size.height);
+
+	// Set the aspect ratio multiplier.
+	uniforms()->aspectRatioMultiplier = float(modals.aspect_ratio / viewAspectRatio);
+
+	// Also work out the proper zoom. Somehow?
+	const double fitWidthZoom = (viewAspectRatio / modals.aspect_ratio) / modals.visible_area.size.width;
+	const double fitHeightZoom = 1.0 / modals.visible_area.size.height;
+
+	// The differing signs for offset below reflect the inverted coordinate system in Metal.
+	uniforms()->zoom = float(std::min(fitWidthZoom, fitHeightZoom));
+	uniforms()->offset.x = -modals.visible_area.origin.x;
+	uniforms()->offset.y = -modals.visible_area.origin.y;
 }
 
 - (void)setModals:(const Outputs::Display::ScanTarget::Modals &)modals {
diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
index fa780d6c2..32faf8b6c 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal	
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal	
@@ -26,6 +26,10 @@ struct Uniforms {
 	// Provides conversions to and from RGB for the active colour space.
 	float3x3 toRGB;
 	float3x3 fromRGB;
+
+	// Provides zoom and offset to scale the source data.
+	float zoom;
+	float2 offset;
 };
 
 // MARK: - Structs used for receiving data from the emulation.
@@ -97,8 +101,11 @@ vertex SourceInterpolator scanToDisplay(	constant Uniforms &uniforms [[buffer(1)
 	) / 32.0;
 
 	// Hence determine this quad's real shape, using vertexID to pick a corner.
+	float2 position2d = start + (float(vertexID&2) * 0.5) * tangent + (float(vertexID&1) - 0.5) * normal * uniforms.lineWidth;
+	position2d = (position2d + uniforms.offset) * uniforms.zoom  * float2(uniforms.aspectRatioMultiplier, 1.0);
+	position2d = position2d * float2(2.0, -2.0) + float2(-1.0, 1.0);
 	output.position = float4(
-		((start + (float(vertexID&2) * 0.5) * tangent + (float(vertexID&1) - 0.5) * normal * uniforms.lineWidth) * float2(2.0, -2.0) + float2(-1.0, 1.0)) * float2(uniforms.aspectRatioMultiplier, 1.0),
+		position2d,
 		0.0,
 		1.0
 	);