diff --git a/Lib/distutils/extension.py b/Lib/distutils/extension.py
index 53ca8fd0c57..6af18108012 100644
--- a/Lib/distutils/extension.py
+++ b/Lib/distutils/extension.py
@@ -103,10 +103,11 @@ class Extension:
                   optional=None,
                   **kw                      # To catch unknown keywords
                  ):
-        assert isinstance(name, str), "'name' must be a string"
-        assert (isinstance(sources, list) and
-                all(isinstance(v, str) for v in sources)), \
-                "'sources' must be a list of strings"
+        if not isinstance(name, str):
+            raise AssertionError("'name' must be a string")
+        if not (isinstance(sources, list) and
+                all(isinstance(v, str) for v in sources)):
+            raise AssertionError("'sources' must be a list of strings")
 
         self.name = name
         self.sources = sources
diff --git a/Misc/NEWS b/Misc/NEWS
index 77e3ac6acae..6b4dac506bc 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -349,6 +349,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #6545: Removed assert statements in distutils.Extension, so the 
+  behavior is similar when used with -O.
+
 - unittest has been split up into a package.  All old names should still work.
 
 - Issue #6431: Make Fraction type return NotImplemented when it doesn't