diff --git a/3rd_party/libsrp6a-sha512/Makefile.am b/3rd_party/libsrp6a-sha512/Makefile.am
index 8c6e2f5..d304585 100644
--- a/3rd_party/libsrp6a-sha512/Makefile.am
+++ b/3rd_party/libsrp6a-sha512/Makefile.am
@@ -9,7 +9,7 @@
 
 AM_CFLAGS = -DHAVE_CONFIG_H
 if HAVE_OPENSSL
-AM_CFLAGS += -DOPENSSL=1 -DOPENSSL_ENGINE=1 $(openssl_CFLAGS)
+AM_CFLAGS += -DOPENSSL=1 $(openssl_CFLAGS)
 else
 if HAVE_GCRYPT
 AM_CFLAGS += -DGCRYPT=1 $(libgcrypt_CFLAGS)
diff --git a/3rd_party/libsrp6a-sha512/t_math.c b/3rd_party/libsrp6a-sha512/t_math.c
index 88ae12f..e655daa 100644
--- a/3rd_party/libsrp6a-sha512/t_math.c
+++ b/3rd_party/libsrp6a-sha512/t_math.c
@@ -39,7 +39,8 @@
 typedef BN_CTX * BigIntegerCtx;
 typedef BN_MONT_CTX * BigIntegerModAccel;
 #include <limits.h>
-# ifdef OPENSSL_ENGINE
+# ifndef OPENSSL_NO_ENGINE
+#  define OPENSSL_ENGINE
 #  include "openssl/engine.h"
 static ENGINE * default_engine = NULL;
 # endif /* OPENSSL_ENGINE */
@@ -951,7 +952,7 @@
 BigIntegerResult
 BigIntegerInitialize()
 {
-#if OPENSSL_VERSION_NUMBER >= 0x00907000
+#if OPENSSL_VERSION_NUMBER >= 0x00907000 && defined(OPENSSL_ENGINE)
   ENGINE_load_builtin_engines();
 #endif
   return BIG_INTEGER_SUCCESS;