diff --git a/src/atom.cpp b/src/atom.cpp
index 315097261b8177734ebdaef368f7139678d8f456..9958fefc88bee926e9c6e90730e6a32107d84559 100644
--- a/src/atom.cpp
+++ b/src/atom.cpp
@@ -2044,9 +2044,7 @@ void Atom::delete_callback(const char *id, int flag)
 {
   if (id == NULL) return;
 
-  int ifix;
-  for (ifix = 0; ifix < modify->nfix; ifix++)
-    if (strcmp(id,modify->fix[ifix]->id) == 0) break;
+  int ifix = modify->find_fix(id);
 
   // compact the list of callbacks
 
@@ -2054,6 +2052,8 @@ void Atom::delete_callback(const char *id, int flag)
     int match;
     for (match = 0; match < nextra_grow; match++)
       if (extra_grow[match] == ifix) break;
+    if ((nextra_grow == 0) || (match == nextra_grow))
+      error->all(FLERR,"Trying to delete non-existent Atom::grow() callback");
     for (int i = match; i < nextra_grow-1; i++)
       extra_grow[i] = extra_grow[i+1];
     nextra_grow--;
@@ -2062,6 +2062,8 @@ void Atom::delete_callback(const char *id, int flag)
     int match;
     for (match = 0; match < nextra_restart; match++)
       if (extra_restart[match] == ifix) break;
+    if ((nextra_restart == 0) || (match == nextra_restart))
+      error->all(FLERR,"Trying to delete non-existent Atom::restart() callback");
     for (int i = match; i < nextra_restart-1; i++)
       extra_restart[i] = extra_restart[i+1];
     nextra_restart--;
@@ -2070,6 +2072,8 @@ void Atom::delete_callback(const char *id, int flag)
     int match;
     for (match = 0; match < nextra_border; match++)
       if (extra_border[match] == ifix) break;
+    if ((nextra_border == 0) || (match == nextra_border))
+      error->all(FLERR,"Trying to delete non-existent Atom::border() callback");
     for (int i = match; i < nextra_border-1; i++)
       extra_border[i] = extra_border[i+1];
     nextra_border--;