diff --git a/jerry-core/parser/js/lexer.cpp b/jerry-core/parser/js/lexer.cpp
index d07becc02..dc2ac2949 100644
--- a/jerry-core/parser/js/lexer.cpp
+++ b/jerry-core/parser/js/lexer.cpp
@@ -166,9 +166,8 @@ adjust_string_ptrs (literal lit, size_t diff)
 }
 
 static literal
-add_current_token_to_string_cache (void)
+add_string_to_string_cache (const ecma_char_t* str, ecma_length_t length)
 {
-  const ecma_length_t length = (ecma_length_t) (buffer - token_start);
   if (strings_cache_used_size + length * sizeof (ecma_char_t) >= strings_cache_size)
   {
     strings_cache_size = mem_heap_recommend_allocation_size (strings_cache_used_size
@@ -183,13 +182,19 @@ add_current_token_to_string_cache (void)
     }
     strings_cache = temp;
   }
-  strncpy ((char *) (strings_cache + strings_cache_used_size), token_start, length);
+  strncpy ((char *) (strings_cache + strings_cache_used_size), (const char*) str, length);
   (strings_cache + strings_cache_used_size)[length] = '\0';
   const literal res = create_literal_from_zt (strings_cache + strings_cache_used_size, length);
   strings_cache_used_size = (size_t) (((size_t) length + 1) * sizeof (ecma_char_t) + strings_cache_used_size);
   return res;
 }
 
+static literal
+add_current_token_to_string_cache (void)
+{
+  return add_string_to_string_cache ((ecma_char_t*) token_start, (ecma_length_t) (buffer - token_start));
+}
+
 static token
 convert_current_token_to_token (token_type tt)
 {
@@ -535,7 +540,7 @@ lexer_get_strings_cache (void)
 }
 
 void
-lexer_add_literal_if_not_present (literal lit)
+lexer_add_keyword_or_numeric_literal_if_not_present (literal lit)
 {
   for (literal_index_t i = 0; i < STACK_SIZE (literals); i++)
   {
@@ -544,6 +549,12 @@ lexer_add_literal_if_not_present (literal lit)
       return;
     }
   }
+
+  if (lit.type == LIT_STR)
+  {
+    lit = add_string_to_string_cache (lit.data.lp.str, lit.data.lp.length);
+  }
+
   STACK_PUSH (literals, lit);
 }
 
diff --git a/jerry-core/parser/js/lexer.h b/jerry-core/parser/js/lexer.h
index 2497a5551..40b3e4009 100644
--- a/jerry-core/parser/js/lexer.h
+++ b/jerry-core/parser/js/lexer.h
@@ -175,7 +175,7 @@ token lexer_prev_token (void);
 
 const literal *lexer_get_literals (void);
 const ecma_char_t *lexer_get_strings_cache (void);
-void lexer_add_literal_if_not_present (literal);
+void lexer_add_keyword_or_numeric_literal_if_not_present (literal);
 literal_index_t lexer_get_literals_count (void);
 literal lexer_get_literal_by_id (literal_index_t);
 literal_index_t lexer_lookup_literal_uid (literal lit);
diff --git a/jerry-core/parser/js/parser.cpp b/jerry-core/parser/js/parser.cpp
index a98573dc4..3babf7d87 100644
--- a/jerry-core/parser/js/parser.cpp
+++ b/jerry-core/parser/js/parser.cpp
@@ -226,14 +226,14 @@ parse_property_name (void)
     case TOK_SMALL_INT:
     {
       const literal lit = create_literal_from_num ((ecma_number_t) token_data ());
-      lexer_add_literal_if_not_present (lit);
+      lexer_add_keyword_or_numeric_literal_if_not_present (lit);
       const literal_index_t lit_id = lexer_lookup_literal_uid (lit);
       return literal_operand (lit_id);
     }
     case TOK_KEYWORD:
     {
       const literal lit = create_literal_from_str_compute_len (lexer_keyword_to_string ((keyword) token_data ()));
-      lexer_add_literal_if_not_present (lit);
+      lexer_add_keyword_or_numeric_literal_if_not_present (lit);
       const literal_index_t lit_id = lexer_lookup_literal_uid (lit);
       return literal_operand (lit_id);
     }
@@ -2486,7 +2486,8 @@ skip_braces (void)
       skip_newlines ();
       if (token_is (TOK_COLON))
       {
-        lexer_add_literal_if_not_present (create_literal_from_str_compute_len (lexer_keyword_to_string (kw)));
+        lexer_add_keyword_or_numeric_literal_if_not_present (
+          create_literal_from_str_compute_len (lexer_keyword_to_string (kw)));
       }
       else
       {
@@ -2505,7 +2506,8 @@ skip_braces (void)
           skip_newlines ();
           if (token_is (TOK_OPEN_PAREN))
           {
-            lexer_add_literal_if_not_present (create_literal_from_str_compute_len (lexer_keyword_to_string (kw)));
+            lexer_add_keyword_or_numeric_literal_if_not_present (
+              create_literal_from_str_compute_len (lexer_keyword_to_string (kw)));
           }
           else
           {