diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index 5adc128..bad8839 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -24,6 +24,7 @@
     chachapoly.c
     cipher.c
     cipher_wrap.c
+    constant_time.c
     cmac.c
     ctr_drbg.c
     des.c