diff --git a/modules/io/tests/test_io_pdb.cc b/modules/io/tests/test_io_pdb.cc
index 053705f01f820d376dff3da00209fe2d7f5d5a25..9be98cdba349f54f49ac5727e3c34e228d018d22 100644
--- a/modules/io/tests/test_io_pdb.cc
+++ b/modules/io/tests/test_io_pdb.cc
@@ -203,7 +203,6 @@ BOOST_AUTO_TEST_CASE(anisou_record)
   BOOST_CHECK_CLOSE( 0.0120, props.anisou(2, 2), 1e-4);    
 }
 
-
 BOOST_AUTO_TEST_CASE(only_66_cols)
 {
   String fname("testfiles/pdb/short.pdb");
@@ -324,6 +323,22 @@ BOOST_AUTO_TEST_CASE(write_ter)
                             "testfiles/pdb/ter-out.pdb"));
 }
 
+BOOST_AUTO_TEST_CASE(write_conect)
+{
+  // this scope is required to force the writer stream to be closed before
+  // opening the file again in compare_files. Avoids a race condition.
+  {
+    PDBReader reader(String("testfiles/pdb/conect.pdb"));
+    PDBWriter writer(String("testfiles/pdb/conect-out.pdb"));
+    mol::EntityHandle ent=mol::CreateEntity();
+    reader.Import(ent);
+    conop::Conopology& conop_inst=conop::Conopology::Instance();
+    conop_inst.ConnectAll(conop_inst.GetBuilder(), ent);
+    writer.Write(ent);
+  }
+  BOOST_CHECK(compare_files("testfiles/pdb/conect.pdb",
+                            "testfiles/pdb/conect-out.pdb"));
+}
 
 BOOST_AUTO_TEST_CASE(res_name_too_long)
 {
diff --git a/modules/io/tests/testfiles/pdb/conect.pdb b/modules/io/tests/testfiles/pdb/conect.pdb
new file mode 100644
index 0000000000000000000000000000000000000000..b4ce6bd8e3855a2a79ccdcfa6424bf6ad796525c
--- /dev/null
+++ b/modules/io/tests/testfiles/pdb/conect.pdb
@@ -0,0 +1,46 @@
+ATOM      1  N   VAL A   1      -8.585  17.971  25.103  0.50 11.44           N  
+ATOM      2  CA  VAL A   1      -8.253  17.023  24.068  0.50 12.65           C  
+ATOM      3  C   VAL A   1      -7.312  17.705  23.054  0.50 16.06           C  
+ATOM      4  O   VAL A   1      -7.544  18.799  22.596  0.50 12.36           O  
+ATOM      5  CB  VAL A   1      -9.457  16.377  23.387  0.50 12.94           C  
+ATOM      6  CG1 VAL A   1      -9.264  14.902  23.055  0.50 11.08           C  
+ATOM      7  CG2 VAL A   1     -10.739  16.533  24.224  0.50 13.21           C  
+ATOM      8  N   VAL A   2      -6.277  16.910  22.755  0.50 16.75           N  
+ATOM      9  CA  VAL A   2      -5.196  17.143  21.863  0.50 16.61           C  
+ATOM     10  C   VAL A   2      -4.253  18.199  22.473  0.50 19.00           C  
+ATOM     11  O   VAL A   2      -4.434  18.654  23.600  0.50 17.27           O  
+ATOM     12  CB  VAL A   2      -5.589  17.486  20.437  0.50 18.24           C  
+ATOM     13  CG1 VAL A   2      -7.059  17.853  20.200  0.50 19.12           C  
+ATOM     14  CG2 VAL A   2      -4.672  18.535  19.802  0.50 14.29           C  
+TER      15      VAL A   2                                                      
+HETATM   16  N   PS0 A   3     -11.234  16.802  30.197  0.50  7.63           N  
+HETATM   17  CA  PS0 A   3     -11.284  16.497  28.779  0.50  6.15           C  
+HETATM   18  C   PS0 A   3     -10.818  17.753  28.010  0.50  8.61           C  
+HETATM   19  OS  PS0 A   3     -11.697  18.822  28.249  0.50  4.53           O  
+HETATM   20  CB  PS0 A   3     -12.670  16.079  28.322  0.50 12.53           C  
+HETATM   21  CG  PS0 A   3     -13.432  14.971  29.048  0.50 11.04           C  
+HETATM   22  CD1 PS0 A   3     -13.076  13.629  28.983  0.50 10.33           C  
+HETATM   23  CD2 PS0 A   3     -14.560  15.373  29.807  0.50 12.71           C  
+HETATM   24  CE1 PS0 A   3     -13.818  12.638  29.661  0.50 11.11           C  
+HETATM   25  CE2 PS0 A   3     -15.300  14.380  30.483  0.50 14.32           C  
+HETATM   26  CZ  PS0 A   3     -14.917  13.043  30.412  0.50 10.61           C  
+HETATM   27  CM  PS0 A   3      -9.405  18.196  28.546  0.50  6.25           C  
+HETATM   28  O   HOH A   4      -3.126  40.621  48.726  1.00 47.60           O  
+HETATM   29  O   HOH A   5      -2.279  35.565  45.117  1.00 43.93           O  
+HETATM   30  O   HOH A   6       5.765  35.848  41.846  1.00 36.24           O  
+HETATM   31  O   HOH A   7     -12.666  40.044  22.441  1.00 41.24           O  
+HETATM   32  O   HOH A   8      -4.462  37.411  18.124  1.00 30.94           O  
+HETATM   33  O   HOH A   9      -1.109  26.454  19.470  1.00 39.06           O  
+CONECT   16   17
+CONECT   17   16   18   20
+CONECT   18   17   19   27
+CONECT   19   18
+CONECT   20   17   21
+CONECT   21   20   22   23
+CONECT   22   21   24
+CONECT   23   21   25
+CONECT   24   22   26
+CONECT   25   23   26
+CONECT   26   24   25
+CONECT   27   18
+END   
\ No newline at end of file