warning: o_max could be used unintializied

diff --git a/src/modules/module-combine-sink.c b/src/modules/module-combine-sink.c
index 2ccd9eb..11a260b 100644
--- a/src/modules/module-combine-sink.c
+++ b/src/modules/module-combine-sink.c
@@ -257,7 +257,7 @@ static void adjust_rates(struct userdata *u) {
     uint32_t idx;
     unsigned n = 0;
     pa_usec_t now;
-    struct output *o_max;
+    struct output *o_max = NULL;
 
     pa_assert(u);
     pa_sink_assert_ref(u->sink);
@@ -334,7 +334,7 @@ static void adjust_rates(struct userdata *u) {
     /* The target selection ensures, that at least one of the
      * sinks will use the base rate and all other sinks are set
      * relative to it. */
-    if (max_sink_latency > min_total_latency)
+    if ((o_max != NULL) && (max_sink_latency > min_total_latency))
         target_latency = o_max->total_latency;
     else
         target_latency = min_total_latency;