diff --git a/cs677/final/mpi-fractals.cc b/cs677/final/mpi-fractals.cc
index 0fc808b..05c8757 100644
--- a/cs677/final/mpi-fractals.cc
+++ b/cs677/final/mpi-fractals.cc
@@ -75,13 +75,13 @@ bool createWindow(int width, int height,
     }
     SDL_WM_SetCaption(PROGNAME, PROGNAME);
 
-    *pixels = (Uint32 *) screen->pixels;
+    *pixels = (Uint32 *) (*screen)->pixels;
 
     return true;
 }
 
 void getSizes(int * rank, int * size)
 {
-    MPI_Comm_rank(rank);
-    MPI_Comm_size(size, MPI_COMM_WORLD);
+    MPI_Comm_rank(MPI_COMM_WORLD, rank);
+    MPI_Comm_size(MPI_COMM_WORLD, size);
 }