diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 053bb73863d..20ebcfbcdf6 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -652,7 +652,10 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			values[20] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
 			values[21] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
 			values[22] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);
-			values[23] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
+			if (beentry->st_sslstatus->ssl_clientdn[0])
+				values[23] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
+			else
+				nulls[23] = true;
 		}
 		else
 		{
diff --git a/src/test/ssl/t/001_ssltests.pl b/src/test/ssl/t/001_ssltests.pl
index 74a5da578a2..bbddb8e2b76 100644
--- a/src/test/ssl/t/001_ssltests.pl
+++ b/src/test/ssl/t/001_ssltests.pl
@@ -316,7 +316,7 @@ command_like([
 	'-c', "SELECT * FROM pg_stat_ssl WHERE pid = pg_backend_pid()"
 			 ],
 			 qr{^pid,ssl,version,cipher,bits,compression,clientdn\n
-				^\d+,t,TLSv[\d.]+,[\w-]+,\d+,f,$}mx,
+				^\d+,t,TLSv[\d.]+,[\w-]+,\d+,f,_null_$}mx,
 			 'pg_stat_ssl view without client certificate');
 
 ### Server-side tests.