diff --git a/include/openssl/crypto.h b/include/openssl/crypto.h
index 28700379..5207a126 100644
--- a/include/openssl/crypto.h
+++ b/include/openssl/crypto.h
@@ -21,6 +21,10 @@
  * mem.h. */
 #include <openssl/mem.h>
 
+/* Upstream OpenSSL defines |CRYPTO_LOCK|, etc., in crypto.h rather than
+ * thread.h. */
+#include <openssl/thread.h>
+
 
 #if defined(__cplusplus)
 extern "C" {