diff --git a/configure.ac b/configure.ac
index 3d8e15bd..399cdf4e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -943,6 +943,7 @@ if test "${with_crypto_library}" = "openssl"; then
 			RSA_meth_set_priv_enc \
 			RSA_meth_set_priv_dec \
 			RSA_meth_set_init \
+			RSA_meth_set_sign \
 			RSA_meth_set_finish \
 			RSA_meth_set0_app_data \
 			RSA_meth_get0_app_data \
diff --git a/src/openvpn/openssl_compat.h b/src/openvpn/openssl_compat.h
index f5328c4c..d2c8d4a6 100644
--- a/src/openvpn/openssl_compat.h
+++ b/src/openvpn/openssl_compat.h
@@ -585,6 +585,26 @@ RSA_meth_set_init(RSA_METHOD *meth, int (*init) (RSA *rsa))
 }
 #endif
 
+#if !(defined HAVE_RSA_MATH_SET_SIGN)
+/**
+ * Set the init function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param sign               The sign function
+ * @return                   1 on success, 0 on error
+ */
+static inline
+int RSA_meth_set_sign(RSA_METHOD *meth,
+                      int (*sign) (int type, const unsigned char *m,
+                                   unsigned int m_length,
+                                   unsigned char *sigret, unsigned int *siglen,
+                                   const RSA *rsa))
+{
+    meth->rsa_sign = sign;
+    return 1;
+}
+#endif
+
 #if !defined(HAVE_RSA_METH_SET_FINISH)
 /**
  * Set the finish function of an RSA_METHOD object