diff --git a/exec.c b/exec.c
index 54cd70ac1e..31d2dc79bc 100644
--- a/exec.c
+++ b/exec.c
@@ -2374,9 +2374,7 @@ static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr)
     if (l > access_size_max) {
         l = access_size_max;
     }
-    if (l & (l - 1)) {
-        l = 1 << (qemu_fls(l) - 1);
-    }
+    l = pow2floor(l);
 
     return l;
 }