diff --git a/target/s390x/mem_helper.c b/target/s390x/mem_helper.c
index 4ed0b65751..2326f0bdb9 100644
--- a/target/s390x/mem_helper.c
+++ b/target/s390x/mem_helper.c
@@ -61,7 +61,7 @@ static inline uint32_t adj_len_to_page(uint32_t len, uint64_t addr)
 {
 #ifndef CONFIG_USER_ONLY
     if ((addr & ~TARGET_PAGE_MASK) + len - 1 >= TARGET_PAGE_SIZE) {
-        return -addr & ~TARGET_PAGE_MASK;
+        return -(addr | TARGET_PAGE_MASK);
     }
 #endif
     return len;