diff --git a/Bio/PDB/ic_rebuild.py b/Bio/PDB/ic_rebuild.py
index 2f6856fa3e9..f4c9c6e3193 100644
--- a/Bio/PDB/ic_rebuild.py
+++ b/Bio/PDB/ic_rebuild.py
@@ -7,7 +7,12 @@
 """Convert XYZ Structure to internal coordinates and back, test result."""
 
 import re
-import itertools
+try:
+    from itertools import zip_longest
+except ImportError:
+    from itertools import izip_longest as zip_longest
+
+# import itertools
 
 try:
     import numpy
@@ -281,9 +286,9 @@ def compare_residues(e0, e1, verbose=False):
     cmpdict["pass"] = None
     cmpdict["report"] = None
 
-    for r0, r1 in itertools.zip_longest(e0.get_residues(), e1.get_residues()):
+    for r0, r1 in zip_longest(e0.get_residues(), e1.get_residues()):
         if 2 == r0.is_disordered() == r1.is_disordered():
-            for dr0, dr1 in itertools.zip_longest(
+            for dr0, dr1 in zip_longest(
                 r0.child_dict.values(), r1.child_dict.values()
             ):
                 _cmp_res(dr0, dr1, verbose, cmpdict)
diff --git a/Bio/PDB/internal_coords.py b/Bio/PDB/internal_coords.py
index 97b1852f97f..87eda6f69c0 100644
--- a/Bio/PDB/internal_coords.py
+++ b/Bio/PDB/internal_coords.py
@@ -2004,7 +2004,7 @@ def __init__(self, *args, **kwargs):
             As for Edron, plus optional 'len1', 'angle2', 'len3'
             keyworded values.
         """
-        super().__init__(*args, **kwargs)
+        super(Hedron, self).__init__(*args, **kwargs)
 
         # print('initialising', self.id)
 
@@ -2202,7 +2202,7 @@ def __init__(self, *args, **kwargs):
         Acceptable input:
             As for Edron, plus optional 'dihedral1' keyworded angle value.
         """
-        super().__init__(*args, **kwargs)
+        super(Dihedron, self).__init__(*args, **kwargs)
 
         # hedra making up this dihedron; set by self:_set_hedra()
         self.hedron1 = None