diff --git a/src/shrpx_ssl.cc b/src/shrpx_ssl.cc
index c3b6e9b7..80e1cfbd 100644
--- a/src/shrpx_ssl.cc
+++ b/src/shrpx_ssl.cc
@@ -73,9 +73,11 @@ namespace shrpx {
 namespace ssl {
 
 #if !OPENSSL_101_API
+namespace {
 const unsigned char *ASN1_STRING_get0_data(ASN1_STRING *x) {
   return ASN1_STRING_data(x);
 }
+} // namespace
 #endif // !OPENSSL_101_API
 
 namespace {
diff --git a/src/ssl_compat.h b/src/ssl_compat.h
index 4b015624..c81b8c3b 100644
--- a/src/ssl_compat.h
+++ b/src/ssl_compat.h
@@ -24,7 +24,9 @@
  */
 #ifndef OPENSSL_COMPAT_H
 
+#include <openssl/opensslv.h>
+
 #define OPENSSL_101_API                                                        \
-  (!defined(LIBRESSL_VERSION_NUMBER) && OPENSSL_VERSION_NUMBER >= 0x10100005L)
+  (!defined(LIBRESSL_VERSION_NUMBER) && OPENSSL_VERSION_NUMBER >= 0x1010000fL)
 
 #endif // OPENSSL_COMPAT_H