diff --git a/uc.c b/uc.c
index 7e2d5fa1..2c8f9f1d 100644
--- a/uc.c
+++ b/uc.c
@@ -588,6 +588,10 @@ uc_err uc_mem_map(uc_engine *uc, uint64_t address, size_t size, uint32_t perms)
         // invalid memory mapping
         return UC_ERR_ARG;
 
+    // address cannot wrapp around
+    if (address + size - 1 < address)
+        return UC_ERR_ARG;
+
     // address must be aligned to uc->target_page_size
     if ((address & uc->target_page_align) != 0)
         return UC_ERR_ARG;
@@ -845,7 +849,7 @@ MemoryRegion *memory_mapping(struct uc_struct* uc, uint64_t address)
         return uc->mapped_blocks[i];
 
     for(i = 0; i < uc->mapped_block_count; i++) {
-        if (address >= uc->mapped_blocks[i]->addr && address < uc->mapped_blocks[i]->end) {
+        if (address >= uc->mapped_blocks[i]->addr && address <= uc->mapped_blocks[i]->end - 1) {
             // cache this index for the next query
             uc->mapped_block_cache_index = i;
             return uc->mapped_blocks[i];