diff --git a/lib/perf-counter.c b/lib/perf-counter.c
index 7bd783451ca..b700e492bcc 100644
--- a/lib/perf-counter.c
+++ b/lib/perf-counter.c
@@ -39,9 +39,9 @@ static int fd__ = 0;
 uint64_t
 perf_counter_read(uint64_t *counter)
 {
-    if (fd__ > 0) {
-        read(fd__, counter, sizeof(*counter));
-    } else {
+    size_t size = sizeof *counter;
+
+    if (fd__ <= 0 || read(fd__, counter, size) < size) {
         *counter = 0;
     }