diff --git a/util/cacheinfo.c b/util/cacheinfo.c
index 3cd080b83d..eebe1ce9c5 100644
--- a/util/cacheinfo.c
+++ b/util/cacheinfo.c
@@ -107,7 +107,7 @@ static void sys_cache_info(int *isize, int *dsize)
 static void arch_cache_info(int *isize, int *dsize)
 {
     if (*isize == 0 || *dsize == 0) {
-        unsigned long ctr;
+        uint64_t ctr;
 
         /* The real cache geometry is in CCSIDR_EL1/CLIDR_EL1/CSSELR_EL1,
            but (at least under Linux) these are marked protected by the