diff --git a/Carpet/src/Poison.cc b/Carpet/src/Poison.cc
index 12fc3d3..39a989a 100644
--- a/Carpet/src/Poison.cc
+++ b/Carpet/src/Poison.cc
@@ -131,12 +131,16 @@ void PoisonGroup(cGH const *const cctkGH, int const group,
     END_LOCAL_MAP_LOOP;

     // mark as invalid
-    for (int var = 0; var < nvar; ++var) {
-      int const map0 = 0;
-      ggf *const ff = arrdata.AT(group).AT(map0).data.AT(var);
-      assert(ff);
-      for (int tl = min_tl; tl <= max_tl; ++tl) {
-        ff->set_valid(mglevel, reflevel, tl, CCTK_VALID_NOWHERE);
+    // Exclude CCTK_ARRAY from this
+    if (CCTK_GroupTypeI(group) != CCTK_ARRAY)
+    {
+      for (int var = 0; var < nvar; ++var) {
+        int const map0 = 0;
+        ggf *const ff = arrdata.AT(group).AT(map0).data.AT(var);
+        assert(ff);
+        for (int tl = min_tl; tl <= max_tl; ++tl) {
+          ff->set_valid(mglevel, reflevel, tl, CCTK_VALID_NOWHERE);
+        }
       }
     }