diff --git a/src/util/u_cpu_detect.c b/src/util/u_cpu_detect.c
index 87f47cda931..4faaf52703a 100644
--- a/src/util/u_cpu_detect.c
+++ b/src/util/u_cpu_detect.c
@@ -136,7 +136,7 @@ check_os_altivec_support(void)
    int sels[2] = {CTL_MACHDEP, CPU_ALTIVEC};
 #endif
    int has_vu = 0;
-   int len = sizeof (has_vu);
+   size_t len = sizeof (has_vu);
    int err;
 
    err = sysctl(sels, 2, &has_vu, &len, NULL, 0);