diff --git a/src/label_map.cpp b/src/label_map.cpp
index a9ffd60877..174f16a7ec 100644
--- a/src/label_map.cpp
+++ b/src/label_map.cpp
@@ -369,35 +369,35 @@ void LabelMap::read_restart(FILE *fp)
   for (int i = 0; i < natomtypes; i++) {
     charlabel = read_string(fp);
     typelabel[i] = charlabel;
-    typelabel_map[charlabel] = i + 1;
+    if (strlen(charlabel) > 0) typelabel_map[charlabel] = i + 1;
     delete[] charlabel;
   }
 
   for (int i = 0; i < nbondtypes; i++) {
     charlabel = read_string(fp);
     btypelabel[i] = charlabel;
-    btypelabel_map[charlabel] = i + 1;
+    if (strlen(charlabel) > 0) btypelabel_map[charlabel] = i + 1;
     delete[] charlabel;
   }
 
   for (int i = 0; i < nangletypes; i++) {
     charlabel = read_string(fp);
     atypelabel[i] = charlabel;
-    atypelabel_map[charlabel] = i + 1;
+    if (strlen(charlabel) > 0) atypelabel_map[charlabel] = i + 1;
     delete[] charlabel;
   }
 
   for (int i = 0; i < ndihedraltypes; i++) {
     charlabel = read_string(fp);
     dtypelabel[i] = charlabel;
-    dtypelabel_map[charlabel] = i + 1;
+    if (strlen(charlabel) > 0) dtypelabel_map[charlabel] = i + 1;
     delete[] charlabel;
   }
 
   for (int i = 0; i < nimpropertypes; i++) {
     charlabel = read_string(fp);
     itypelabel[i] = charlabel;
-    itypelabel_map[charlabel] = i + 1;
+    if (strlen(charlabel) > 0) itypelabel_map[charlabel] = i + 1;
     delete[] charlabel;
   }
 }