diff --git a/shims/libcrypto/crypto.c b/shims/libcrypto/crypto.c
index 2c143c5..6e2e52b 100644
--- a/shims/libcrypto/crypto.c
+++ b/shims/libcrypto/crypto.c
@@ -15,6 +15,7 @@
  */
 
 #include <stddef.h>
+#include <time.h>
 
 extern void *sk_new_null(void);
 void *OPENSSL_sk_new_null(void) {
@@ -35,3 +36,8 @@
 void* OPENSSL_sk_value(const void *sk, size_t i) {
     return sk_value(sk, i);
 }
+
+extern void *ASN1_TIME_set(void *s, time_t time);
+void *ASN1_TIME_set_posix(void *s, int64_t posix_time) {
+    return ASN1_TIME_set(s, posix_time);
+}