diff --git a/gpu/Color.cu b/gpu/Color.cu
index 389a8dc7..7fd87e30 100644
--- a/gpu/Color.cu
+++ b/gpu/Color.cu
@@ -4145,7 +4145,7 @@ extern "C" void ScaLBL_Color_BC_Z(int *list, int *Map, double *Phi, double *Den,
 
 extern "C" void ScaLBL_CopySlice_z(double *Phi, int Nx, int Ny, int Nz, int Source, int Dest){
 	int GRID = Nx*Ny / 512 + 1;
-	dvc_ScaLBL_CopySlice_z<<<GRID,512>>>(Phi,Nx,Ny,Nz,Slice,Dest);
+	dvc_ScaLBL_CopySlice_z<<<GRID,512>>>(Phi,Nx,Ny,Nz,Source,Dest);
 }