diff --git a/util/hbitmap.c b/util/hbitmap.c
index d5aca5159f..8d402c59d9 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -759,6 +759,9 @@ bool hbitmap_merge(const HBitmap *a, const HBitmap *b, HBitmap *result)
         }
     }
 
+    /* Recompute the dirty count */
+    result->count = hb_count_between(result, 0, result->size - 1);
+
     return true;
 }