diff --git a/crypto/CMakeLists.txt b/crypto/CMakeLists.txt
index 496d64bba5..128a7748f4 100644
--- a/crypto/CMakeLists.txt
+++ b/crypto/CMakeLists.txt
@@ -734,7 +734,7 @@ set(
 	x509/x_all.c
 )
 
-set(COMPAT_SRC "")
+set(COMPAT_SRC empty.c)
 
 if(UNIX)
 	set(CRYPTO_SRC ${CRYPTO_SRC} crypto_lock.c)
diff --git a/tls/CMakeLists.txt b/tls/CMakeLists.txt
index 33ae1849d0..919b1fa7bb 100644
--- a/tls/CMakeLists.txt
+++ b/tls/CMakeLists.txt
@@ -14,7 +14,7 @@ set(
 	tls_verify.c
 )
 
-set(TLS_COMPAT_SRC "")
+set(TLS_COMPAT_SRC empty.c)
 
 if(WIN32)
 	set(