diff -dupr a/setup.py b/setup.py
--- a/setup.py	2021-02-09 13:46:16.138626317 +0100
+++ b/setup.py	2021-02-09 13:46:51.116065599 +0100
@@ -360,7 +360,7 @@ ext_modules = [
     Extension("Crypto.Cipher._raw_eksblowfish",
         include_dirs=['src/'],
         define_macros=[('EKS',None),],
-        sources=["src/blowfish.c"],
+        sources=["src/blowfish_eks.c"],
         py_limited_api=True),
     Extension("Crypto.Cipher._raw_cast",
         include_dirs=['src/'],
@@ -442,7 +442,8 @@ ext_modules = [
     # Math
     Extension("Crypto.Math._modexp",
         include_dirs=['src/'],
-        sources=['src/modexp.c', 'src/siphash.c', 'src/modexp_utils.c', 'src/mont.c'],
+        sources=['src/modexp.c', 'src/siphash.c', 'src/modexp_utils.c',
+                 'src/mont_math.c'],
         py_limited_api=True,
         ),
 ]