diff --git a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal
index 7fa69016e..7bc5f57ef 100644
--- a/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal	
+++ b/OSBindings/Mac/Clock Signal/ScanTarget/ScanTarget.metal	
@@ -91,8 +91,8 @@ struct Line {
 struct SourceInterpolator {
 	float4 position [[position]];
 	float2 textureCoordinates;
-	half unitColourPhase;		// i.e. one unit per circle.
-	half colourPhase;			// i.e. 2*pi units per circle, just regular radians.
+	float unitColourPhase;		// i.e. one unit per circle.
+	float colourPhase;			// i.e. 2*pi units per circle, just regular radians.
 	half colourAmplitude [[flat]];
 };