diff --git a/lib/LWP/Protocol/https.pm b/lib/LWP/Protocol/https.pm
index 645e828..7098f64 100644
--- a/lib/LWP/Protocol/https.pm
+++ b/lib/LWP/Protocol/https.pm
@@ -29,6 +29,9 @@ sub _extra_sock_opts
         }
     }
     if ($ssl_opts{SSL_verify_mode}) {
+        if ($ENV{NIX_SSL_CERT_FILE}) {
+            $ssl_opts{SSL_ca_file} //= $ENV{NIX_SSL_CERT_FILE};
+        }
         unless (exists $ssl_opts{SSL_ca_file} || exists $ssl_opts{SSL_ca_path}) {
             if ($Net::HTTPS::SSL_SOCKET_CLASS eq 'IO::Socket::SSL'
                 && defined &IO::Socket::SSL::default_ca