diff --git a/src/libruntime/serializer.h b/src/libruntime/serializer.h
index f437ce1a1..e47008a84 100644
--- a/src/libruntime/serializer.h
+++ b/src/libruntime/serializer.h
@@ -21,9 +21,9 @@
 
 void serializer_init (void);
 
-uint8_t serializer_dump_strings (const char **, uint8_t);
+uint16_t serializer_dump_strings (const char **, uint8_t);
 
-void serializer_dump_nums (const int32_t *, uint8_t, uint8_t, uint8_t);
+void serializer_dump_nums (const int32_t *, uint8_t, uint16_t, uint8_t);
 
 void serializer_dump_opcode (OPCODE);
 
diff --git a/src/libruntime/target/linux/deserializer.c b/src/libruntime/target/linux/deserializer.c
index eaa50a2ce..1056fc88b 100644
--- a/src/libruntime/target/linux/deserializer.c
+++ b/src/libruntime/target/linux/deserializer.c
@@ -22,7 +22,8 @@ uint8_t num_size = 0;
 const ecma_char_t *
 deserialize_string_by_id (uint8_t id)
 {
-  uint8_t size, *data, offset;
+  uint8_t size, *data;
+  uint16_t offset;
 
   if (bytecode_data == NULL)
     return NULL;
@@ -34,17 +35,18 @@ deserialize_string_by_id (uint8_t id)
 
   data = bytecode_data;
 
-  data += id + 1;
+  data += id * 2 + 1;
 
-  offset = *data;
+  offset = *((uint16_t *) data);
 
-  return bytecode_data + offset;
+  return ((const ecma_char_t *) bytecode_data + offset);
 }
 
 int 
 deserialize_num_by_id (uint8_t id)
 {
-  uint8_t str_size, str_offset, *data;
+  uint16_t str_size, str_offset;
+  uint8_t *data;
 
   str_size = *bytecode_data;
   if (id < str_size)
@@ -55,8 +57,9 @@ deserialize_num_by_id (uint8_t id)
   
   if (num_data == NULL)
     {
-      data = bytecode_data + str_size;
-      str_offset = *data;
+      // Go to last string's offset
+      data = (uint8_t *) (bytecode_data + str_size * 2 - 1);
+      str_offset = *((uint16_t *) data);
       data = bytecode_data + str_offset;
 
       while (*data)
diff --git a/src/libruntime/target/linux/serializer.c b/src/libruntime/target/linux/serializer.c
index 801fc2d13..a5b983249 100644
--- a/src/libruntime/target/linux/serializer.c
+++ b/src/libruntime/target/linux/serializer.c
@@ -14,6 +14,7 @@
  */
 
 #include "serializer.h"
+#include "parser.h"
 #include "jerry-libc.h"
 #include "bytecode-linux.h"
 #include "deserializer.h"
@@ -41,32 +42,35 @@ serializer_init (void)
 {
 }
 
-uint8_t
+uint16_t
 serializer_dump_strings (const char *strings[], uint8_t size)
 {
   uint8_t i;
-  uint8_t offset = (uint8_t) (size + 1), res;
+  uint16_t offset = (uint16_t) (size * 2 + 1), res;
 
   __printf ("STRINGS %d:\n", size);
   for (i = 0; i < size; i++)
     {
-      __printf ("%3d %3d %20s\n", i, offset, strings[i]);
-      offset = (uint8_t) (offset + __strlen (strings[i]) + 1);
+      __printf ("%3d %5d %20s\n", i, offset, strings[i]);
+      offset = (uint16_t) (offset + __strlen (strings[i]) + 1);
     }
 
   bytecode_data = mem_heap_alloc_block (offset, MEM_HEAP_ALLOC_SHORT_TERM);
   res = offset;
 
   bytecode_data[0] = size;
-  offset = (uint8_t) (size + 1);
+  offset = (uint16_t) (size * 2 + 1);
   for (i = 0; i < size; i++)
     {
-      bytecode_data[i + 1] = offset;
-      offset = (uint8_t) (offset + __strlen (strings[i]) + 1);
+      *((uint16_t *) (bytecode_data + i * 2 + 1)) = offset;
+      offset = (uint16_t) (offset + __strlen (strings[i]) + 1);
     }
 
   for (i = 0; i < size; i++)
-    __strncpy ((void *) (bytecode_data + bytecode_data[i + 1]), strings[i], __strlen (strings[i]) + 1);
+    {
+      offset = *((uint16_t *) (bytecode_data + i * 2 + 1));
+      __strncpy ((char *) (bytecode_data + offset), strings[i], __strlen (strings[i]) + 1);
+    }
 
 #ifndef JERRY_NDEBUG
   for (i = 0; i < size; i++)
@@ -79,21 +83,22 @@ serializer_dump_strings (const char *strings[], uint8_t size)
 }
 
 void 
-serializer_dump_nums (const int32_t nums[], uint8_t size, uint8_t offset, uint8_t strings_num)
+serializer_dump_nums (const int32_t nums[], uint8_t size, uint16_t offset, uint8_t strings_num)
 {
-  uint8_t i, *data, num_offset;
+  uint8_t i, *data;
 
-  num_offset = (uint8_t) (offset + size + 1);
   __printf ("NUMS %d:\n", size);
   for (i = 0; i < size; i++)
     {
-      __printf ("%3d %3d %7d\n", i + strings_num, num_offset, nums[i]);
-      num_offset = (uint8_t) (num_offset + 4);
+      __printf ("%3d %7d\n", i + strings_num, nums[i]);
     }
 
   __printf ("\n");
 
   data = mem_heap_alloc_block ((size_t) (offset + size * 4 + 1), MEM_HEAP_ALLOC_LONG_TERM);
+  if (!data)
+    parser_fatal (ERR_MEMORY);
+  
   __memcpy (data, bytecode_data, offset);
   mem_heap_free_block (bytecode_data);
   bytecode_data = data;
diff --git a/src/libruntime/target/stm32f4/deserializer.c b/src/libruntime/target/stm32f4/deserializer.c
index 192d3d2e4..c6013a63a 100644
--- a/src/libruntime/target/stm32f4/deserializer.c
+++ b/src/libruntime/target/stm32f4/deserializer.c
@@ -24,7 +24,8 @@ uint8_t num_size = 0;
 const ecma_char_t *
 deserialize_string_by_id (uint8_t id)
 {
-  uint8_t size, *data, offset;
+  uint8_t size, *data;
+  uint16_t offset;
 
   if (bytecode_data == NULL)
     return NULL;
@@ -36,17 +37,18 @@ deserialize_string_by_id (uint8_t id)
 
   data = bytecode_data;
 
-  data += id + 1;
+  data += id * 2 + 1;
 
-  offset = *data;
+  offset = *((uint16_t *) data);
 
-  return bytecode_data + offset;
+  return ((const ecma_char_t *) bytecode_data + offset);
 }
 
 int 
 deserialize_num_by_id (uint8_t id)
 {
-  uint8_t str_size, str_offset, *data;
+  uint16_t str_size, str_offset;
+  uint8_t *data;
 
   str_size = *bytecode_data;
   if (id < str_size)
@@ -57,8 +59,9 @@ deserialize_num_by_id (uint8_t id)
   
   if (num_data == NULL)
     {
-      data = bytecode_data + str_size;
-      str_offset = *data;
+      // Go to last string's offset
+      data = (uint8_t *) (bytecode_data + str_size * 2 - 1);
+      str_offset = *((uint16_t *) data);
       data = bytecode_data + str_offset;
 
       while (*data)
diff --git a/src/libruntime/target/stm32f4/serializer.c b/src/libruntime/target/stm32f4/serializer.c
index 5a0ba8af2..41ee302d3 100644
--- a/src/libruntime/target/stm32f4/serializer.c
+++ b/src/libruntime/target/stm32f4/serializer.c
@@ -14,6 +14,7 @@
  */
 
 #include "serializer.h"
+#include "parser.h"
 #include "globals.h"
 #include "serializer.h"
 #include "jerry-libc.h"
@@ -27,30 +28,33 @@ serializer_init (void)
 {
 }
 
-uint8_t
+uint16_t
 serializer_dump_strings (const char *strings[], uint8_t size)
 {
   uint8_t i;
-  uint8_t offset = (uint8_t) (size + 1), res;
+  uint16_t offset = (uint8_t) (size * 2 + 1), res;
 
   for (i = 0; i < size; i++)
     {
-      offset = (uint8_t) (offset + __strlen (strings[i]) + 1);
+      offset = (uint16_t) (offset + __strlen (strings[i]) + 1);
     }
 
   bytecode_data = mem_heap_alloc_block (offset, MEM_HEAP_ALLOC_SHORT_TERM);
   res = offset;
 
   bytecode_data[0] = size;
-  offset = (uint8_t) (size + 1);
+  offset = (uint16_t) (size * 2 + 1);
   for (i = 0; i < size; i++)
     {
-      bytecode_data[i + 1] = offset;
-      offset = (uint8_t) (offset + __strlen (strings[i]) + 1);
+      *((uint16_t *) (bytecode_data + i * 2 + 1)) = offset;
+      offset = (uint16_t) (offset + __strlen (strings[i]) + 1);
     }
 
   for (i = 0; i < size; i++)
-    __strncpy ((void *) (bytecode_data + bytecode_data[i + 1]), strings[i], __strlen (strings[i]) + 1);
+    {
+      offset = *((uint16_t *) (bytecode_data + i * 2 + 1));
+      __strncpy ((char *) (bytecode_data + offset), strings[i], __strlen (strings[i]) + 1);
+    }
 
 #ifndef JERRY_NDEBUG
   for (i = 0; i < size; i++)
@@ -63,11 +67,14 @@ serializer_dump_strings (const char *strings[], uint8_t size)
 }
 
 void 
-serializer_dump_nums (const int32_t nums[], uint8_t size, uint8_t offset, uint8_t strings_num __unused)
+serializer_dump_nums (const int32_t nums[], uint8_t size, uint16_t offset, uint8_t strings_num __unused)
 {
   uint8_t i, *data;
 
   data = mem_heap_alloc_block ((size_t) (offset + size * 4 + 1), MEM_HEAP_ALLOC_LONG_TERM);
+  if (!data)
+    parser_fatal (ERR_MEMORY);
+  
   __memcpy (data, bytecode_data, offset);
   mem_heap_free_block (bytecode_data);
 
diff --git a/src/main.c b/src/main.c
index cfe99a642..52ccd1f2f 100644
--- a/src/main.c
+++ b/src/main.c
@@ -36,7 +36,7 @@ parser_run (const char *script_source, size_t script_source_size __unused)
   const char *strings[MAX_STRINGS];
   int32_t nums[MAX_NUMS];
   uint8_t strings_num, nums_count;
-  uint8_t offset;
+  uint16_t offset;
   const OPCODE *opcodes;
 
   TODO( Consider using script_source_size in lexer to check buffer boundaries );
diff --git a/tests/unit/test_addition_opcode_number_operands.c b/tests/unit/test_addition_opcode_number_operands.c
index 0ebeadfe4..747b78dc7 100644
--- a/tests/unit/test_addition_opcode_number_operands.c
+++ b/tests/unit/test_addition_opcode_number_operands.c
@@ -41,7 +41,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);
diff --git a/tests/unit/test_assignment_opcode.c b/tests/unit/test_assignment_opcode.c
index ef8950da2..e96796a5c 100644
--- a/tests/unit/test_assignment_opcode.c
+++ b/tests/unit/test_assignment_opcode.c
@@ -46,7 +46,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);
diff --git a/tests/unit/test_division_opcode.c b/tests/unit/test_division_opcode.c
index 32e22cf0d..2bedfe736 100644
--- a/tests/unit/test_division_opcode.c
+++ b/tests/unit/test_division_opcode.c
@@ -41,7 +41,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);
diff --git a/tests/unit/test_multiplication_opcode.c b/tests/unit/test_multiplication_opcode.c
index fdb31c203..c95abb483 100644
--- a/tests/unit/test_multiplication_opcode.c
+++ b/tests/unit/test_multiplication_opcode.c
@@ -41,7 +41,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);
diff --git a/tests/unit/test_remainder_opcode.c b/tests/unit/test_remainder_opcode.c
index d9380fbc4..e82209ac9 100644
--- a/tests/unit/test_remainder_opcode.c
+++ b/tests/unit/test_remainder_opcode.c
@@ -41,7 +41,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);
diff --git a/tests/unit/test_substraction_opcode.c b/tests/unit/test_substraction_opcode.c
index f47833de7..a81e0ebd4 100644
--- a/tests/unit/test_substraction_opcode.c
+++ b/tests/unit/test_substraction_opcode.c
@@ -41,7 +41,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);
diff --git a/tests/unit/test_var_decl_opcode_in_decl_lex_env.c b/tests/unit/test_var_decl_opcode_in_decl_lex_env.c
index 274ad6f77..b4a25f091 100644
--- a/tests/unit/test_var_decl_opcode_in_decl_lex_env.c
+++ b/tests/unit/test_var_decl_opcode_in_decl_lex_env.c
@@ -39,7 +39,7 @@ main( int __unused argc,
   const char *strings[] = { "a",
                             "b" };
   int nums [] = { 2 };
-  uint8_t offset = serializer_dump_strings( strings, 2);
+  uint16_t offset = serializer_dump_strings( strings, 2);
   serializer_dump_nums( nums, 1, offset, 2);
 
   init_int( test_program);