diff --git a/ext/openssl/extconf.rb b/ext/openssl/extconf.rb
index 75da65c..98f3bd3 100644
--- a/ext/openssl/extconf.rb
+++ b/ext/openssl/extconf.rb
@@ -122,6 +122,10 @@ def find_openssl_library
   OpenSSL.check_func_or_macro("ENGINE_load_#{name}", "openssl/engine.h")
 }
 
+# newer, OpenSSL-dubbed versions of SSLeay*() exist, and the old names may be
+# removed in future versions of OpenSSL
+have_func("SSLeay_version")
+
 # added in 0.9.8X
 have_func("EVP_CIPHER_CTX_new")
 have_func("EVP_CIPHER_CTX_free")
@@ -188,6 +192,10 @@ def find_openssl_library
 OpenSSL.check_func_or_macro("SSL_CTX_set_min_proto_version", "openssl/ssl.h")
 have_func("SSL_CTX_get_security_level")
 have_func("X509_get0_notBefore")
+have_func("X509_set1_notBefore")
+have_func("X509_set1_notAfter")
+have_func("X509_CRL_set1_lastUpdate")
+have_func("X509_CRL_set1_nextUpdate")
 have_func("SSL_SESSION_get_protocol_version")
 
 Logging::message "=== Checking done. ===\n"
diff --git a/ext/openssl/ossl.c b/ext/openssl/ossl.c
index c22966d..7d48944 100644
--- a/ext/openssl/ossl.c
+++ b/ext/openssl/ossl.c
@@ -1010,10 +1010,12 @@ Init_openssl(void)
      */
     /* CRYPTO_malloc_init(); */
     /* ENGINE_load_builtin_engines(); */
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
     OpenSSL_add_ssl_algorithms();
     OpenSSL_add_all_algorithms();
     ERR_load_crypto_strings();
     SSL_load_error_strings();
+#endif
 
     /*
      * FIXME:
@@ -1048,7 +1050,11 @@ Init_openssl(void)
     /*
      * Version of OpenSSL the ruby OpenSSL extension is running with
      */
+#ifdef HAVE_SSLEAY_VERSION
     rb_define_const(mOSSL, "OPENSSL_LIBRARY_VERSION", rb_str_new2(SSLeay_version(SSLEAY_VERSION)));
+#else
+    rb_define_const(mOSSL, "OPENSSL_LIBRARY_VERSION", rb_str_new2(OpenSSL_version(OPENSSL_VERSION)));
+#endif
 
     /*
      * Version number of OpenSSL the ruby OpenSSL extension was built with
diff --git a/ext/openssl/ossl.h b/ext/openssl/ossl.h
index 78eddd0..184a52e 100644
--- a/ext/openssl/ossl.h
+++ b/ext/openssl/ossl.h
@@ -19,6 +19,11 @@
 #include <ruby/thread.h>
 #include <openssl/opensslv.h>
 #include <openssl/err.h>
+#include <openssl/bn.h>
+#include <openssl/evp.h>
+#include <openssl/rsa.h>
+#include <openssl/dsa.h>
+#include <openssl/dh.h>
 #include <openssl/asn1.h>
 #include <openssl/x509v3.h>
 #include <openssl/ssl.h>
diff --git a/ext/openssl/ossl_cipher.c b/ext/openssl/ossl_cipher.c
index c2f0927..ed3ccdd 100644
--- a/ext/openssl/ossl_cipher.c
+++ b/ext/openssl/ossl_cipher.c
@@ -31,6 +31,10 @@
     GetCipher((obj), (ctx)); \
 } while (0)
 
+# if OPENSSL_VERSION_NUMBER >= 0x10100000L
+#  define EVP_CIPHER_CTX_flags(c)       EVP_CIPHER_flags(EVP_CIPHER_CTX_cipher(c))
+# endif
+
 /*
  * Classes
  */
diff --git a/ext/openssl/ossl_engine.c b/ext/openssl/ossl_engine.c
index e840bfd..d9069b1 100644
--- a/ext/openssl/ossl_engine.c
+++ b/ext/openssl/ossl_engine.c
@@ -147,7 +147,9 @@ ossl_engine_s_load(int argc, VALUE *argv, VALUE klass)
 #ifdef HAVE_ENGINE_LOAD_OPENBSD_DEV_CRYPTO
     OSSL_ENGINE_LOAD_IF_MATCH(openbsd_dev_crypto);
 #endif
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
     OSSL_ENGINE_LOAD_IF_MATCH(openssl);
+#endif
     rb_warning("no such builtin loader for `%"PRIsVALUE"'", name);
     return Qnil;
 #endif /* HAVE_ENGINE_LOAD_BUILTIN_ENGINES */
@@ -165,7 +167,9 @@ ossl_engine_s_load(int argc, VALUE *argv, VALUE klass)
 static VALUE
 ossl_engine_s_cleanup(VALUE self)
 {
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
     ENGINE_cleanup();
+#endif
     return Qnil;
 }
 
diff --git a/ext/openssl/ossl_x509cert.c b/ext/openssl/ossl_x509cert.c
index 87086a7..4b6253e 100644
--- a/ext/openssl/ossl_x509cert.c
+++ b/ext/openssl/ossl_x509cert.c
@@ -478,7 +478,11 @@ ossl_x509_set_not_before(VALUE self, VALUE time)
 
     GetX509(self, x509);
     asn1time = ossl_x509_time_adjust(NULL, time);
+#ifdef HAVE_X509_SET1_NOTBEFORE
+    if (!X509_set1_notBefore(x509, asn1time)) {
+#else
     if (!X509_set_notBefore(x509, asn1time)) {
+#endif
 	ASN1_TIME_free(asn1time);
 	ossl_raise(eX509CertError, "X509_set_notBefore");
     }
@@ -517,7 +521,11 @@ ossl_x509_set_not_after(VALUE self, VALUE time)
 
     GetX509(self, x509);
     asn1time = ossl_x509_time_adjust(NULL, time);
+#ifdef HAVE_X509_SET1_NOTAFTER
+    if (!X509_set1_notAfter(x509, asn1time)) {
+#else
     if (!X509_set_notAfter(x509, asn1time)) {
+#endif
 	ASN1_TIME_free(asn1time);
 	ossl_raise(eX509CertError, "X509_set_notAfter");
     }
diff --git a/ext/openssl/ossl_x509crl.c b/ext/openssl/ossl_x509crl.c
index 035025a..ee0c930 100644
--- a/ext/openssl/ossl_x509crl.c
+++ b/ext/openssl/ossl_x509crl.c
@@ -237,7 +237,11 @@ ossl_x509crl_set_last_update(VALUE self, VALUE time)
 
     GetX509CRL(self, crl);
     asn1time = ossl_x509_time_adjust(NULL, time);
+#ifdef HAVE_X509_CRL_SET1_LASTUPDATE
+    if (!X509_CRL_set1_lastUpdate(crl, asn1time)) {
+#else
     if (!X509_CRL_set_lastUpdate(crl, asn1time)) {
+#endif
 	ASN1_TIME_free(asn1time);
 	ossl_raise(eX509CRLError, "X509_CRL_set_lastUpdate");
     }
@@ -264,7 +268,11 @@ ossl_x509crl_set_next_update(VALUE self, VALUE time)
 
     GetX509CRL(self, crl);
     asn1time = ossl_x509_time_adjust(NULL, time);
+#ifdef HAVE_X509_CRL_SET1_NEXTUPDATE
+    if (!X509_CRL_set1_nextUpdate(crl, asn1time)) {
+#else
     if (!X509_CRL_set_nextUpdate(crl, asn1time)) {
+#endif
 	ASN1_TIME_free(asn1time);
 	ossl_raise(eX509CRLError, "X509_CRL_set_nextUpdate");
     }