diff --git a/Src/Model3/SoundBoard.cpp b/Src/Model3/SoundBoard.cpp
index 157d59e..25b6645 100644
--- a/Src/Model3/SoundBoard.cpp
+++ b/Src/Model3/SoundBoard.cpp
@@ -337,7 +337,7 @@ void SCSP68KIRQCallback(int irqLevel)
 // SCSP callback for running the 68K
 int SCSP68KRunCallback(int numCycles)
 {
-	return numCycles - M68KRun(numCycles);
+	return M68KRun(numCycles) - numCycles;
 }