diff --git a/src/sigar.c b/src/sigar.c
index cb7be994..c5b4f53c 100644
--- a/src/sigar.c
+++ b/src/sigar.c
@@ -111,7 +111,7 @@ SIGAR_DECLARE(int) sigar_proc_cpu_get(sigar_t *sigar, sigar_pid_t pid,
     sigar_cache_entry_t *entry;
     sigar_proc_cpu_t *prev;
     sigar_uint64_t otime, time_now = sigar_time_now_millis();
-    sigar_int64_t time_diff, total_diff;
+    sigar_uint64_t time_diff, total_diff;
     int status;
 
     if (!sigar->proc_cpu) {