diff --git a/linux-user/mmap.c b/linux-user/mmap.c
index 6163f1a0d1..4bcfaf7894 100644
--- a/linux-user/mmap.c
+++ b/linux-user/mmap.c
@@ -1029,9 +1029,9 @@ static int mmap_reserve_or_unmap(abi_ulong start, abi_ulong len)
     void *host_start;
     int prot;
 
-    last = start + len - 1;
+    last = ROUND_UP(start + len, TARGET_PAGE_SIZE) - 1;
     real_start = start & -host_page_size;
-    real_last = ROUND_UP(last, host_page_size) - 1;
+    real_last = ROUND_UP(last + 1, host_page_size) - 1;
 
     /*
      * If guest pages remain on the first or last host pages,