diff --git a/WHATS_NEW b/WHATS_NEW
index ca9e6fa6a..9682d22c6 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.178 - 
 =====================================
+  Fix evaluation of maximal region size for mirror log.
   Enhance mirror log size estimation and use smaller size when possible.
   Fix incorrect mirror log size calculation on 32bit arch.
   Enhnace preloading tree creating.
diff --git a/lib/metadata/mirror.c b/lib/metadata/mirror.c
index 61076192a..db2883bfc 100644
--- a/lib/metadata/mirror.c
+++ b/lib/metadata/mirror.c
@@ -161,17 +161,17 @@ uint32_t adjusted_mirror_region_size(struct cmd_context *cmd,
 				     uint32_t extent_size, uint32_t extents,
 				     uint32_t region_size, int internal, int clustered)
 {
-	uint64_t region_max;
-	uint64_t region_min, region_min_pow2;
+	uint64_t region_max, region_min;
+	uint32_t region_min_pow2;
 
-	region_max = (UINT64_C(1) << (ffs((int)extents) - 1)) * (UINT64_C(1) << (ffs((int)extent_size) - 1));
+	region_max = (uint64_t) extents * extent_size;
 
 	if (region_max < UINT32_MAX && region_size > region_max) {
-		region_size = (uint32_t) region_max;
+		region_size =  UINT64_C(1) << (31 - clz(region_max));
 		if (!internal)
 			log_print_unless_silent("Using reduced mirror region size of %s",
 						display_size(cmd, region_size));
-                else
+		else
 			log_verbose("Using reduced mirror region size of %s",
 				    display_size(cmd, region_size));
 	}