diff --git a/src/compute_chunk_atom.cpp b/src/compute_chunk_atom.cpp
index fafcf7aee376d6d2fb2ea345e349c5508b6c96e7..925c5fbf81ff1c6340670bf00b8abf34044a9091 100644
--- a/src/compute_chunk_atom.cpp
+++ b/src/compute_chunk_atom.cpp
@@ -493,7 +493,7 @@ ComputeChunkAtom::~ComputeChunkAtom()
 {
   // check nfix in case all fixes have already been deleted
 
-  if (modify->nfix) modify->delete_fix(id_fix);
+  if (id_fix && modify->nfix) modify->delete_fix(id_fix);
   delete [] id_fix;
 
   memory->destroy(chunk);