diff --git a/src/tools/pw-top.c b/src/tools/pw-top.c
index 4df68a86b..e0f558d76 100644
--- a/src/tools/pw-top.c
+++ b/src/tools/pw-top.c
@@ -450,9 +450,11 @@ static const char *print_perc(char *buf, bool active, size_t len, uint64_t val,
 		snprintf(buf, len, " --- ");
 	} else if (val == (uint64_t)-2) {
 		snprintf(buf, len, " +++ ");
+	} else if (quantum == 0.0f) {
+		snprintf(buf, len, " ??? ");
 	} else {
 		float frac = val / 1000000000.f;
-		snprintf(buf, len, "%5.2f", quantum == 0.0f ? 0.0f : frac/quantum);
+		snprintf(buf, len, "%5.2f", frac/quantum);
 	}
 	return buf;
 }
@@ -504,7 +506,7 @@ static void print_node(struct data *d, struct driver *i, struct node *n, int y)
 	if (i->clock.rate.denom)
 		quantum = (float)i->clock.duration * i->clock.rate.num / (float)i->clock.rate.denom;
 	else
-		quantum = 0.0;
+		quantum = 0.0f;
 
 	if (n->measurement.awake >= n->measurement.signal)
 		waiting = n->measurement.awake - n->measurement.signal;