diff --git a/lib/compress/hist.c b/lib/compress/hist.c
index 3692bc250cadbb831133b432094a7115efed848e..917b85df81764db305e3b04e99c0137c55bab7c2 100644
--- a/lib/compress/hist.c
+++ b/lib/compress/hist.c
@@ -37,7 +37,14 @@ void HIST_add(unsigned* count, const void* src, size_t srcSize)
     const BYTE* ip = (const BYTE*)src;
     const BYTE* const end = ip + srcSize;
 
-    while (ip<end) {
+    while ((size_t)(end - ip) >= 4) {
+        count[ip[0]]++;
+        count[ip[1]]++;
+        count[ip[2]]++;
+        count[ip[3]]++;
+        ip += 4;
+    }
+    while (ip < end) {
         count[*ip++]++;
     }
 }