diff --git a/src/info.cpp b/src/info.cpp
index fd8c233868..dc59bdadee 100644
--- a/src/info.cpp
+++ b/src/info.cpp
@@ -887,42 +887,17 @@ bool Info::is_defined(const char *category, const char *name)
   if ((category == nullptr) || (name == nullptr)) return false;
 
   if (strcmp(category,"compute") == 0) {
-    int ncompute = modify->ncompute;
-    Compute **compute = modify->compute;
-    for (int i=0; i < ncompute; ++i) {
-      if (strcmp(compute[i]->id,name) == 0)
-        return true;
-    }
+    if (modify->get_compute_by_id(name)) return true;
   } else if (strcmp(category,"dump") == 0) {
-    int ndump = output->ndump;
-    Dump **dump = output->dump;
-    for (int i=0; i < ndump; ++i) {
-      if (strcmp(dump[i]->id,name) == 0)
-        return true;
-    }
+    if (output->get_dump_by_id(name)) return true;
   } else if (strcmp(category,"fix") == 0) {
-    for (const auto &fix : modify->get_fix_list()) {
-      if (strcmp(fix->id,name) == 0)
-        return true;
-    }
+    if (modify->get_fix_by_id(name)) return true;
   } else if (strcmp(category,"group") == 0) {
-    int ngroup = group->ngroup;
-    char **names = group->names;
-    for (int i=0; i < ngroup; ++i) {
-      if (strcmp(names[i],name) == 0)
-        return true;
-    }
+    if (group->find(name) >= 0) return true;
   } else if (strcmp(category,"region") == 0) {
-    for (auto &reg : domain->get_region_list())
-      if (strcmp(reg->id,name) == 0) return true;
+    if (domain->get_region_by_id(name)) return true;
   } else if (strcmp(category,"variable") == 0) {
-    int nvar = input->variable->nvar;
-    char **names = input->variable->names;
-
-    for (int i=0; i < nvar; ++i) {
-      if (strcmp(names[i],name) == 0)
-        return true;
-    }
+    if (input->variable->find(name) >= 0) return true;
   } else error->all(FLERR,"Unknown category for info is_defined(): {}", category);
 
   return false;
diff --git a/src/library.cpp b/src/library.cpp
index 8692c35848..771508ff1b 100644
--- a/src/library.cpp
+++ b/src/library.cpp
@@ -4841,6 +4841,7 @@ set to an empty string, otherwise 1.
  */
 int lammps_id_name(void *handle, const char *category, int idx, char *buffer, int buf_size) {
   auto lmp = (LAMMPS *) handle;
+  if (idx < 0) return 0;
 
   if (strcmp(category,"compute") == 0) {
     auto icompute = lmp->modify->get_compute_by_index(idx);
@@ -4849,8 +4850,9 @@ int lammps_id_name(void *handle, const char *category, int idx, char *buffer, in
       return 1;
     }
   } else if (strcmp(category,"dump") == 0) {
-    if ((idx >=0) && (idx < lmp->output->ndump)) {
-      strncpy(buffer, lmp->output->dump[idx]->id, buf_size);
+    auto idump = lmp->output->get_dump_by_index(idx);
+    if (idump) {
+      strncpy(buffer, idump->id, buf_size);
       return 1;
     }
   } else if (strcmp(category,"fix") == 0) {