diff --git a/jerry-core/ecma/base/ecma-property-hashmap.c b/jerry-core/ecma/base/ecma-property-hashmap.c
index 97c3fd234b..d9c0047d10 100644
--- a/jerry-core/ecma/base/ecma-property-hashmap.c
+++ b/jerry-core/ecma/base/ecma-property-hashmap.c
@@ -310,8 +310,13 @@ ecma_property_hashmap_insert (ecma_object_t *object_p, /**< object */
   bits_p += (entry_index >> 3);
   mask = (uint32_t) (1 << (entry_index & 0x7));
 
-  hashmap_p->null_count--;
-  JERRY_ASSERT (hashmap_p->null_count > 0);
+  if (!(*bits_p & mask))
+  {
+    /* Deleted entries also has ECMA_NULL_POINTER
+     * value, but they are not NULL values. */
+    hashmap_p->null_count--;
+    JERRY_ASSERT (hashmap_p->null_count > 0);
+  }
 
   hashmap_p->unused_count--;
   JERRY_ASSERT (hashmap_p->unused_count > 0);
diff --git a/jerry-core/parser/js/js-parser.c b/jerry-core/parser/js/js-parser.c
index 922afabb2a..11beda7032 100644
--- a/jerry-core/parser/js/js-parser.c
+++ b/jerry-core/parser/js/js-parser.c
@@ -323,7 +323,7 @@ parser_compute_indicies (parser_context_t *context_p, /**< context */
     {
       if (!(literal_p->status_flags & LEXER_FLAG_NO_REG_STORE))
       {
-        JERRY_ASSERT (register_count < PARSER_MAXIMUM_NUMBER_OF_REGISTERS);
+        JERRY_ASSERT (register_count <= PARSER_MAXIMUM_NUMBER_OF_REGISTERS);
         /* This var literal can be stored in a register. */
         literal_p->prop.index = register_index;
         register_index++;