diff --git a/modules/io/src/mol/mmcif_reader.cc b/modules/io/src/mol/mmcif_reader.cc
index 6ed02b70651e1eaf9858e7142943de5d639034b5..a5233dca4c7afb899b0c3adbb35159ba8308619f 100644
--- a/modules/io/src/mol/mmcif_reader.cc
+++ b/modules/io/src/mol/mmcif_reader.cc
@@ -129,7 +129,6 @@ bool MMCifParser::OnBeginLoop(const StarLoopDesc& header)
     this->TryStoreIdx(CARTN_Y, "Cartn_y", header);
     this->TryStoreIdx(CARTN_Z, "Cartn_z", header);
     // optional
-    indices_[PDBX_PDB_INS_CODE] = header.GetIndex("pdbx_PDB_ins_code");
     indices_[OCCUPANCY] = header.GetIndex("occupancy");
     indices_[B_ISO_OR_EQUIV] = header.GetIndex("B_iso_or_equiv");
     indices_[GROUP_PDB] = header.GetIndex("group_PDB");
@@ -201,12 +200,7 @@ bool MMCifParser::ParseAtomIdent(const std::vector<StringRef>& columns,
     }
   }
 
-  if (indices_[PDBX_PDB_INS_CODE] != -1) { // unit test
-    resnum=to_res_num(res_num.second, columns[indices_[PDBX_PDB_INS_CODE]][0]);
-  }
-  else {
-    resnum=to_res_num(res_num.second, ' ');
-  }
+  resnum=to_res_num(res_num.second, ' ');
 
   return true;
 }
diff --git a/modules/io/src/mol/mmcif_reader.hh b/modules/io/src/mol/mmcif_reader.hh
index 93322dd267aac35220d579b0d9c68294cedbb554..b9a191a1695d04b771b225e82efbd55f924ab321 100644
--- a/modules/io/src/mol/mmcif_reader.hh
+++ b/modules/io/src/mol/mmcif_reader.hh
@@ -170,7 +170,6 @@ private:
     CARTN_X,           ///< Coordinates ||IMPORTANT: This 3 entries have to stay
     CARTN_Y,           ///< Coordinates ||together for the parser to work!
     CARTN_Z,           ///< Coordinates ||
-    PDBX_PDB_INS_CODE,
     OCCUPANCY,
     B_ISO_OR_EQUIV,
     GROUP_PDB          ///< record name