1 files changed, 13 insertions, 7 deletions
diff --git a/src/slab.c b/src/slab.c
index 27f6258..53bcabf 100644
--- a/src/slab.c
+++ b/src/slab.c
@@ -60,9 +60,11 @@ CCTK_FILEVERSION(TAT_Slab_slab_c);
 #ifdef CCTK_MPI
 #  if defined CARPET_CARPET
 #    include "Carpet/Carpet/src/carpet_public.h"
-#  elif defined CACTUSPUGH_PUGH
+#  endif
+#  if defined CACTUSPUGH_PUGH
 #    include "CactusPUGH/PUGH/src/include/pugh.h"
-#  else
+#  endif
+#  if ! defined CARPET_CARPET && ! defined CACTUSPUGH_PUGH
 #    error "No supported driver thorn included"
 #  endif
 #endif
@@ -160,12 +162,16 @@ static MPI_Comm get_mpi_comm (cGH * restrict const cctkGH)
 {
 #ifdef CCTK_MPI
 #  if defined CARPET_CARPET
-  return CarpetMPIComm ();
-#  elif defined CACTUSPUGH_PUGH
-  return PUGH_pGH(cctkGH)->PUGH_COMM_WORLD;
-#  else
-#    error "No supported driver thorn included"
+  if (CCTK_IsThornActive ("Carpet")) {
+    return CarpetMPIComm ();
+  }
+#  endif
+#  if defined CACTUSPUGH_PUGH
+  if (CCTK_IsThornActive ("PUGH")) {
+    return PUGH_pGH(cctkGH)->PUGH_COMM_WORLD;
+  }
 #  endif
+  assert (0);
 #else
   return 0;
 #endif