diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index 34fff6e72..9a437ffbf 100644
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -4699,6 +4699,7 @@ static void command_set_sink_or_source_port(pa_pdispatch *pd, uint32_t command,
     CHECK_VALIDITY(c->pstream, !name || pa_namereg_is_valid_name_or_wildcard(name, command == PA_COMMAND_SET_SINK_PORT ? PA_NAMEREG_SINK : PA_NAMEREG_SOURCE), tag, PA_ERR_INVALID);
     CHECK_VALIDITY(c->pstream, idx != PA_INVALID_INDEX || name, tag, PA_ERR_INVALID);
     CHECK_VALIDITY(c->pstream, idx == PA_INVALID_INDEX || !name, tag, PA_ERR_INVALID);
+    CHECK_VALIDITY(c->pstream, (idx != PA_INVALID_INDEX) ^ (name != NULL), tag, PA_ERR_INVALID);
     CHECK_VALIDITY(c->pstream, port, tag, PA_ERR_INVALID);
 
     if (command == PA_COMMAND_SET_SINK_PORT) {