diff --git a/src/libjsparser/lexer.c b/src/libjsparser/lexer.c
index 352134edc..3972b1e87 100644
--- a/src/libjsparser/lexer.c
+++ b/src/libjsparser/lexer.c
@@ -21,6 +21,7 @@
 
 static token saved_token;
 static token empty_token = { .type = TOK_EMPTY, .data.uid = 0 };
+static bool allow_dump_lines = false;
 
 typedef struct
 {
@@ -93,6 +94,9 @@ dump_current_line (void)
 {
   const char *i;
 
+  if (!allow_dump_lines)
+    return;
+
   __printf ("// ");
 
   for (i = buffer; *i != '\n' && *i != 0; i++)
@@ -915,10 +919,11 @@ lexer_dump_buffer_state (void)
 }
 
 void
-lexer_init( const char *source)
+lexer_init (const char *source, bool show_opcodes)
 {
   saved_token = empty_token;
-  lexer_set_source( source);
+  allow_dump_lines = show_opcodes;
+  lexer_set_source (source);
   increase_strings_cache ();
 }
 
diff --git a/src/libjsparser/lexer.h b/src/libjsparser/lexer.h
index 86e5b1788..63f46cb9b 100644
--- a/src/libjsparser/lexer.h
+++ b/src/libjsparser/lexer.h
@@ -147,7 +147,7 @@ typedef struct
 } __packed
 token;
 
-void lexer_init(const char *);
+void lexer_init(const char *, bool);
 void lexer_free (void);
 void lexer_run_first_pass( void);
 token lexer_next_token (void);
diff --git a/src/libruntime/target/linux/serializer.c b/src/libruntime/target/linux/serializer.c
index 260211bc6..c3a538264 100644
--- a/src/libruntime/target/linux/serializer.c
+++ b/src/libruntime/target/linux/serializer.c
@@ -99,10 +99,9 @@ serializer_dump_nums (const int32_t nums[], uint8_t size, uint16_t offset, uint8
         {
           __printf ("%3d %7d\n", i + strings_num, nums[i]);
         }
+      __printf ("\n");
     }
 
-  __printf ("\n");
-
   data = mem_heap_alloc_block ((size_t) (offset + size * 4 + 1), MEM_HEAP_ALLOC_LONG_TERM);
   if (!data)
     parser_fatal (ERR_MEMORY);
@@ -148,6 +147,8 @@ serializer_dump_opcode (OPCODE opcode)
 
       __printf ("\n");
     }
+  else
+    opcode_counter++;
 }
 
 void
diff --git a/src/main.c b/src/main.c
index d9f13c1be..bf5c64b92 100644
--- a/src/main.c
+++ b/src/main.c
@@ -33,7 +33,7 @@
 #define MAX_NUMS 25
 
 static const OPCODE *
-parser_run (const char *script_source, size_t script_source_size __unused)
+parser_run (const char *script_source, size_t script_source_size __unused, bool is_show_opcodes)
 {
   const char *strings[MAX_STRINGS];
   int32_t nums[MAX_NUMS];
@@ -43,7 +43,7 @@ parser_run (const char *script_source, size_t script_source_size __unused)
 
   TODO( Consider using script_source_size in lexer to check buffer boundaries );
 
-  lexer_init( script_source);
+  lexer_init( script_source, is_show_opcodes);
 
   lexer_run_first_pass();
 
@@ -80,7 +80,7 @@ jerry_run (const char *script_source, size_t script_source_size, bool is_parse_o
 
   serializer_init (is_show_opcodes);
 
-  opcodes = parser_run (script_source, script_source_size);
+  opcodes = parser_run (script_source, script_source_size, is_show_opcodes);
 
   if (is_parse_only)
     {