diff --git a/setup.py b/setup.py
index 576c070570359ee0e80586d74e74fbc290f1eec6..a707197cfc95cdd45e474e0f0a6656eb45221e4d 100644
--- a/setup.py
+++ b/setup.py
@@ -112,8 +112,8 @@ def main():
               extra_compile_args=conf["CXXFLAGS"],
               extra_link_args=conf["LDFLAGS"],
               ),
-            ]
-         )
+            ],
+          zip_safe=False)
 
 
 
diff --git a/src/python/tet.py b/src/python/tet.py
index 5eedb842c60584753bc39844e0f5ce884abb2a0d..a3df03dbc3725eb84515b3a8cbab6dc8c1e1708e 100644
--- a/src/python/tet.py
+++ b/src/python/tet.py
@@ -230,7 +230,7 @@ def _is_same_float(a, b, threshold=1e-10):
         a,b = b,a
 
     # now abs(a) <= abs(b) always
-    return abs(b) < threshold or abs(a-b)<threshold*b
+    return abs(b) < threshold or abs(a-b)<threshold*abs(b)
 
 
 
@@ -399,7 +399,9 @@ def generate_extrusion(rz_points, base_shape, closure=EXT_OPEN,
                 if rz_points[i][0] == 0:
                     assert len(ring_points) == 1
                 else:
-                    assert len(ring_points) == len(base_shape)
+                    assert len(ring_points) == len(base_shape), \
+                            ("Ring points length (%d) does not match base shape length (%d)"
+                                    % (len(ring_points), len(base_shape)))
 
                 rings[i] = ring_points