diff --git a/src/immersedBoundary/immersedBoundary/include/immersedBoundaryCourantNo.H b/src/immersedBoundary/immersedBoundary/include/immersedBoundaryCourantNo.H
index 9608db2c8..41707b63a 100644
--- a/src/immersedBoundary/immersedBoundary/include/immersedBoundaryCourantNo.H
+++ b/src/immersedBoundary/immersedBoundary/include/immersedBoundaryCourantNo.H
@@ -36,7 +36,7 @@ scalar velMag = 0.0;
 
 if (mesh.nInternalFaces())
 {
-    surfaceScalarField magPhi = mag(sGamma*phi);
+    surfaceScalarField magPhi = pos(sGamma - 0.5)*mag(phi);
 
     surfaceScalarField SfUfbyDelta =
         mesh.surfaceInterpolation::deltaCoeffs()*magPhi;