diff --git a/contrib/kbipack/CMakeLists.txt b/contrib/kbipack/CMakeLists.txt
index 53147e18ad0e447df9d25c20a7f5125ce31e9d5d..ae9cf789ded851a469b2cc302c552d9144e77e34 100644
--- a/contrib/kbipack/CMakeLists.txt
+++ b/contrib/kbipack/CMakeLists.txt
@@ -8,7 +8,7 @@ set(SRC
   gmp_matrix_io.c
   gmp_matrix.c
   gmp_blas.c
-  mpz.c
+  mpz.cpp
 )
 
 file(GLOB_RECURSE HDR RELATIVE ${CMAKE_SOURCE_DIR}/contrib/kbipack *.h)
diff --git a/contrib/kbipack/mpz.c b/contrib/kbipack/mpz.cpp
similarity index 100%
rename from contrib/kbipack/mpz.c
rename to contrib/kbipack/mpz.cpp