diff -u -r ../otp-OTP-21.0.5/lib/crypto/c_src/otp_test_engine.c ./lib/crypto/c_src/otp_test_engine.c
--- ../otp-OTP-21.0.5/lib/crypto/c_src/otp_test_engine.c	2018-08-10 17:02:51.000000000 +0000
+++ ./lib/crypto/c_src/otp_test_engine.c	2018-08-23 22:15:50.757486039 +0000
@@ -41,7 +41,8 @@
 #if OPENSSL_VERSION_NUMBER >= PACKED_OPENSSL_VERSION(0,9,8,'o') \
 	&& !defined(OPENSSL_NO_EC) \
 	&& !defined(OPENSSL_NO_ECDH) \
-	&& !defined(OPENSSL_NO_ECDSA)
+	&& !defined(OPENSSL_NO_ECDSA) \
+	&& !defined(OPENSSL_NO_ENGINE)
 # define HAVE_EC
 #endif