diff --git a/jerry-core/parser/js/js-parser-internal.h b/jerry-core/parser/js/js-parser-internal.h
index 6c2af6d406..41f8f7f6e3 100644
--- a/jerry-core/parser/js/js-parser-internal.h
+++ b/jerry-core/parser/js/js-parser-internal.h
@@ -86,6 +86,9 @@ typedef enum
   PARSER_MODULE_STORE_IDENT = (1u << 26),     /**< store identifier of the current export statement */
   PARSER_IS_EVAL = (1u << 27),                /**< eval code */
 #endif /* ENABLED (JERRY_ES2015_MODULE_SYSTEM) */
+#ifndef JERRY_NDEBUG
+  PARSER_SCANNING_SUCCESSFUL = (1u << 30),    /**< scanning process was successful */
+#endif /* !JERRY_NDEBUG */
 } parser_general_flags_t;
 
 /**
diff --git a/jerry-core/parser/js/js-parser.c b/jerry-core/parser/js/js-parser.c
index 8889d67191..882d9f3ebc 100644
--- a/jerry-core/parser/js/js-parser.c
+++ b/jerry-core/parser/js/js-parser.c
@@ -2544,6 +2544,10 @@ parser_parse_source (const uint8_t *arg_list_p, /**< function argument list */
     compiled_code_p = parser_post_processing (&context);
     parser_list_free (&context.literal_pool);
 
+#ifndef JERRY_NDEBUG
+    JERRY_ASSERT (context.status_flags & PARSER_SCANNING_SUCCESSFUL);
+#endif /* !JERRY_NDEBUG */
+
 #if ENABLED (JERRY_PARSER_DUMP_BYTE_CODE)
     if (context.is_show_opcodes)
     {
diff --git a/jerry-core/parser/js/js-scanner-internal.h b/jerry-core/parser/js/js-scanner-internal.h
new file mode 100644
index 0000000000..ab1942c032
--- /dev/null
+++ b/jerry-core/parser/js/js-scanner-internal.h
@@ -0,0 +1,73 @@
+/* Copyright JS Foundation and other contributors, http://js.foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef JS_SCANNER_INTERNAL_H
+#define JS_SCANNER_INTERNAL_H
+
+/** \addtogroup parser Parser
+ * @{
+ *
+ * \addtogroup jsparser JavaScript
+ * @{
+ *
+ * \addtogroup jsparser_scanner Scanner
+ * @{
+ */
+
+/**
+ * Generic descriptor which stores only the start position.
+ */
+typedef struct
+{
+  const uint8_t *source_p; /**< start source byte */
+} scanner_source_start_t;
+
+/**
+ * For statement descriptor.
+ */
+typedef struct
+{
+  /** shared fields of for statements */
+  union
+  {
+    const uint8_t *source_p; /**< start source byte */
+    scanner_for_info_t *for_info_p; /**< for info */
+  } u;
+} scanner_for_statement_t;
+
+/**
+ * Switch statement descriptor.
+ */
+typedef struct
+{
+  scanner_case_info_t **last_case_p; /**< last case info */
+} scanner_switch_statement_t;
+
+/**
+ * Scanner context.
+ */
+typedef struct
+{
+  uint8_t mode; /**< scanner mode */
+  scanner_switch_statement_t active_switch_statement; /**< currently active switch statement */
+} scanner_context_t;
+
+/**
+ * @}
+ * @}
+ * @}
+ */
+
+#endif /* !JS_SCANNER_INTERNAL_H */
diff --git a/jerry-core/parser/js/js-scanner-util.c b/jerry-core/parser/js/js-scanner-util.c
index 2259476a43..eed4161a19 100644
--- a/jerry-core/parser/js/js-scanner-util.c
+++ b/jerry-core/parser/js/js-scanner-util.c
@@ -14,6 +14,7 @@
  */
 
 #include "js-parser-internal.h"
+#include "js-scanner-internal.h"
 
 #if ENABLED (JERRY_PARSER)
 
diff --git a/jerry-core/parser/js/js-scanner.c b/jerry-core/parser/js/js-scanner.c
index a5713ae987..3937a24acf 100644
--- a/jerry-core/parser/js/js-scanner.c
+++ b/jerry-core/parser/js/js-scanner.c
@@ -14,6 +14,7 @@
  */
 
 #include "js-parser-internal.h"
+#include "js-scanner-internal.h"
 #include "lit-char-helpers.h"
 
 #if ENABLED (JERRY_PARSER)
@@ -41,6 +42,7 @@ typedef enum
   SCAN_MODE_POST_PRIMARY_EXPRESSION,       /**< scanning post primary expression */
   SCAN_MODE_PRIMARY_EXPRESSION_END,        /**< scanning primary expression end */
   SCAN_MODE_STATEMENT,                     /**< scanning statement */
+  SCAN_MODE_VAR_STATEMENT,                 /**< scanning var statement */
   SCAN_MODE_FUNCTION_ARGUMENTS,            /**< scanning function arguments */
 #if ENABLED (JERRY_ES2015_FUNCTION_PARAMETER_INITIALIZER)
   SCAN_MODE_CONTINUE_FUNCTION_ARGUMENTS,   /**< continue scanning function arguments */
@@ -66,6 +68,9 @@ typedef enum
   SCAN_STACK_PAREN_EXPRESSION,             /**< parent expression group */
   SCAN_STACK_PAREN_STATEMENT,              /**< parent statement group */
   SCAN_STACK_WHILE_START,                  /**< start of "while" iterator */
+  /* The SCANNER_IS_FOR_START macro needs to be updated when the following constants are reordered. */
+  SCAN_STACK_VAR,                          /**< var statement */
+  SCAN_STACK_FOR_VAR_START,                /**< start of "for" iterator with var statement */
   SCAN_STACK_FOR_START,                    /**< start of "for" iterator */
   SCAN_STACK_FOR_CONDITION,                /**< condition part of "for" iterator */
   SCAN_STACK_FOR_EXPRESSION,               /**< expression part of "for" iterator */
@@ -94,41 +99,19 @@ typedef enum
 } scan_stack_modes_t;
 
 /**
- * Generic descriptor which stores only the start position.
+ * Checks whether the stack top is a for statement start.
  */
-typedef struct
-{
-  const uint8_t *source_p; /**< start source byte */
-} scanner_source_start_t;
-
-/**
- * For statement descriptor.
- */
-typedef struct
-{
-  union
-  {
-    const uint8_t *source_p; /**< start source byte */
-    scanner_for_info_t *for_info_p; /**< for info */
-  } u;
-} scanner_for_statement_t;
+#define SCANNER_IS_FOR_START(stack_top) \
+  ((stack_top) >= SCAN_STACK_FOR_VAR_START && (stack_top) <= SCAN_STACK_FOR_START)
 
 /**
- * Switch statement descriptor.
+ * Checks whether token type is "of".
  */
-typedef struct
-{
-  scanner_case_info_t **last_case_p; /**< last case info */
-} scanner_switch_statement_t;
-
-/**
- * Scanner context.
- */
-typedef struct
-{
-  uint8_t mode; /**< scanner mode */
-  scanner_switch_statement_t active_switch_statement; /**< currently active switch statement */
-} scanner_context_t;
+#if ENABLED (JERRY_ES2015_FOR_OF)
+#define SCANNER_IDENTIFIER_IS_OF() (lexer_compare_literal_to_identifier (context_p, "of", 2))
+#else
+#define SCANNER_IDENTIFIER_IS_OF() (false)
+#endif /* ENABLED (JERRY_ES2015_FOR_OF) */
 
 #if ENABLED (JERRY_ES2015_ARROW_FUNCTION)
 
@@ -401,6 +384,12 @@ scanner_scan_primary_expression_end (parser_context_t *context_p, /**< context *
           scanner_context_p->mode = SCAN_MODE_PROPERTY_NAME;
           return true;
         }
+        case SCAN_STACK_VAR:
+        case SCAN_STACK_FOR_VAR_START:
+        {
+          scanner_context_p->mode = SCAN_MODE_VAR_STATEMENT;
+          return false;
+        }
 #if ENABLED (JERRY_ES2015_FUNCTION_PARAMETER_INITIALIZER)
         case SCAN_STACK_FUNCTION_PARAMETERS:
         {
@@ -454,7 +443,7 @@ scanner_scan_primary_expression_end (parser_context_t *context_p, /**< context *
   }
 
   if (LEXER_IS_BINARY_OP_TOKEN (type)
-      && (type != LEXER_KEYW_IN || stack_top != SCAN_STACK_FOR_START))
+      && (type != LEXER_KEYW_IN || !SCANNER_IS_FOR_START (stack_top)))
   {
     scanner_context_p->mode = SCAN_MODE_PRIMARY_EXPRESSION;
     return false;
@@ -462,6 +451,16 @@ scanner_scan_primary_expression_end (parser_context_t *context_p, /**< context *
 
   switch (stack_top)
   {
+    case SCAN_STACK_VAR:
+    {
+      parser_stack_pop_uint8 (context_p);
+
+      if (type == LEXER_EOS)
+      {
+        return true;
+      }
+      /* FALLTHRU */
+    }
     case SCAN_STACK_HEAD:
     case SCAN_STACK_BLOCK_STATEMENT:
     case SCAN_STACK_FUNCTION_STATEMENT:
@@ -527,13 +526,10 @@ scanner_scan_primary_expression_end (parser_context_t *context_p, /**< context *
       scanner_context_p->mode = SCAN_MODE_STATEMENT;
       return false;
     }
+    case SCAN_STACK_FOR_VAR_START:
     case SCAN_STACK_FOR_START:
     {
-      if (type == LEXER_KEYW_IN
-#if ENABLED (JERRY_ES2015_FOR_OF)
-          || lexer_compare_literal_to_identifier (context_p, "of", 2)
-#endif /* ENABLED (JERRY_ES2015_FOR_OF) */
-          || false)
+      if (type == LEXER_KEYW_IN || SCANNER_IDENTIFIER_IS_OF ())
       {
         scanner_for_statement_t for_statement;
 
@@ -869,26 +865,36 @@ scanner_scan_statement (parser_context_t *context_p, /**< context */
 
       scanner_for_statement_t for_statement;
       for_statement.u.source_p = context_p->source_p;
-
-      parser_stack_push (context_p, &for_statement, sizeof (scanner_for_statement_t));
-      parser_stack_push_uint8 (context_p, SCAN_STACK_FOR_START);
+      uint8_t stack_mode = SCAN_STACK_FOR_START;
 
       lexer_next_token (context_p);
+      scanner_context_p->mode = SCAN_MODE_PRIMARY_EXPRESSION;
 
-      if (context_p->token.type == LEXER_SEMICOLON)
+      switch (context_p->token.type)
       {
-        scanner_context_p->mode = SCAN_MODE_PRIMARY_EXPRESSION_END;
-        return true;
+        case LEXER_SEMICOLON:
+        {
+          scanner_context_p->mode = SCAN_MODE_PRIMARY_EXPRESSION_END;
+          break;
+        }
+        case LEXER_KEYW_VAR:
+        {
+          scanner_context_p->mode = SCAN_MODE_VAR_STATEMENT;
+          stack_mode = SCAN_STACK_FOR_VAR_START;
+          break;
+        }
       }
 
-      scanner_context_p->mode = SCAN_MODE_PRIMARY_EXPRESSION;
-      if (context_p->token.type == LEXER_KEYW_VAR)
-      {
-        return false;
-      }
-      return true;
+      parser_stack_push (context_p, &for_statement, sizeof (scanner_for_statement_t));
+      parser_stack_push_uint8 (context_p, stack_mode);
+      return (stack_mode == SCAN_STACK_FOR_START);
     }
     case LEXER_KEYW_VAR:
+    {
+      parser_stack_push_uint8 (context_p, SCAN_STACK_VAR);
+      scanner_context_p->mode = SCAN_MODE_VAR_STATEMENT;
+      return false;
+    }
     case LEXER_KEYW_THROW:
     {
       scanner_context_p->mode = SCAN_MODE_PRIMARY_EXPRESSION;
@@ -1351,6 +1357,10 @@ scanner_scan_all (parser_context_t *context_p) /**< context */
 
       if (type == LEXER_EOS)
       {
+#ifndef JERRY_NDEBUG
+        context_p->status_flags |= PARSER_SCANNING_SUCCESSFUL;
+#endif /* !JERRY_NDEBUG */
+
         if (stack_top == SCAN_STACK_HEAD)
         {
           break;
@@ -1498,6 +1508,59 @@ scanner_scan_all (parser_context_t *context_p) /**< context */
           }
           break;
         }
+        case SCAN_MODE_VAR_STATEMENT:
+        {
+          if (type != LEXER_LITERAL
+              || context_p->token.lit_location.type != LEXER_IDENT_LITERAL)
+          {
+            scanner_raise_error (context_p);
+          }
+
+          lexer_next_token (context_p);
+
+          switch (context_p->token.type)
+          {
+            case LEXER_ASSIGN:
+            {
+              scanner_context.mode = SCAN_MODE_PRIMARY_EXPRESSION;
+              /* FALLTHRU */
+            }
+            case LEXER_COMMA:
+            {
+              lexer_next_token (context_p);
+              continue;
+            }
+            case LEXER_SEMICOLON:
+            case LEXER_RIGHT_BRACE:
+            {
+              scanner_context.mode = SCAN_MODE_PRIMARY_EXPRESSION_END;
+              continue;
+            }
+          }
+
+          if (SCANNER_IS_FOR_START (stack_top))
+          {
+            if (context_p->token.type != LEXER_KEYW_IN && !SCANNER_IDENTIFIER_IS_OF ())
+            {
+              scanner_raise_error (context_p);
+            }
+
+            scanner_context.mode = SCAN_MODE_PRIMARY_EXPRESSION_END;
+            continue;
+          }
+
+          if (context_p->token.type != LEXER_EOS
+              && !(context_p->token.flags & LEXER_WAS_NEWLINE))
+          {
+            scanner_raise_error (context_p);
+          }
+
+          JERRY_ASSERT (stack_top == SCAN_STACK_VAR);
+
+          scanner_context.mode = SCAN_MODE_STATEMENT;
+          parser_stack_pop_uint8 (context_p);
+          continue;
+        }
         case SCAN_MODE_FUNCTION_ARGUMENTS:
         {
           JERRY_ASSERT (stack_top == SCAN_STACK_FUNCTION_STATEMENT
diff --git a/tests/jerry/es2015/class.js b/tests/jerry/es2015/class.js
index 4465f05c3e..42d939ca2e 100644
--- a/tests/jerry/es2015/class.js
+++ b/tests/jerry/es2015/class.js
@@ -236,6 +236,3 @@ assert (G.get() == 11);
 assert (G.set() == 12);
 G.constructor = 30;
 assert (G.constructor === 30);
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/function-rest-parameter.js b/tests/jerry/es2015/function-rest-parameter.js
index 751481817f..35f60c162f 100644
--- a/tests/jerry/es2015/function-rest-parameter.js
+++ b/tests/jerry/es2015/function-rest-parameter.js
@@ -78,6 +78,3 @@ assert (g2 () === 11);
 assert (g2 (1) === 3);
 assert (g2 (1, 2) === 3);
 assert (g2 (1, 2, 3) === 4);
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-01.js b/tests/jerry/es2015/module-export-01.js
index a094fedb7f..90bfff549a 100644
--- a/tests/jerry/es2015/module-export-01.js
+++ b/tests/jerry/es2015/module-export-01.js
@@ -39,6 +39,3 @@ assert (x === 42);
 assert (f(1) === 1);
 var dog = new Dog("Pluto")
 assert(dog.speak() === "Pluto barks.")
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-02.js b/tests/jerry/es2015/module-export-02.js
index 198a148ab8..6fddc5f091 100644
--- a/tests/jerry/es2015/module-export-02.js
+++ b/tests/jerry/es2015/module-export-02.js
@@ -18,6 +18,3 @@ export {aa,} from "module-export-01.js";
 export {bb as b_, cc as c_} from "module-export-01.js";
 export * from "module-export-01.js";
 export default function () {return "default"};
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-03.js b/tests/jerry/es2015/module-export-03.js
index 4ac8be5464..eb8850c36c 100644
--- a/tests/jerry/es2015/module-export-03.js
+++ b/tests/jerry/es2015/module-export-03.js
@@ -24,6 +24,3 @@ export default class {
 }
 
 export * from "module-export-02.js"
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-04.js b/tests/jerry/es2015/module-export-04.js
index 360781cbe1..39d7caecd0 100644
--- a/tests/jerry/es2015/module-export-04.js
+++ b/tests/jerry/es2015/module-export-04.js
@@ -15,6 +15,3 @@
 
 export var x = 41
 export default a = "str"
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-05.js b/tests/jerry/es2015/module-export-05.js
index bf0a0b6844..5a6349c024 100644
--- a/tests/jerry/es2015/module-export-05.js
+++ b/tests/jerry/es2015/module-export-05.js
@@ -16,6 +16,3 @@
 export * from "module-export-01.js";
 export * from "module-export-04.js";
 export default a = "str"
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-06.js b/tests/jerry/es2015/module-export-06.js
index f52854a2b9..8c614a4906 100644
--- a/tests/jerry/es2015/module-export-06.js
+++ b/tests/jerry/es2015/module-export-06.js
@@ -17,6 +17,3 @@ export {}
 export {} from "module-export-01.js";
 export {};
 export {} from "module-export-04.js"
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-export-07.js b/tests/jerry/es2015/module-export-07.js
index 798cc4dd18..39dea13eed 100644
--- a/tests/jerry/es2015/module-export-07.js
+++ b/tests/jerry/es2015/module-export-07.js
@@ -15,6 +15,3 @@
 
 var y, z;
 export default x = y = z = "default";
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-import-01.js b/tests/jerry/es2015/module-import-01.js
index 97424163ee..54f6826f5e 100644
--- a/tests/jerry/es2015/module-import-01.js
+++ b/tests/jerry/es2015/module-import-01.js
@@ -31,6 +31,3 @@ assert (mod.f("str") === "str")
 
 var dog = new mod.Dog("Oddie")
 assert (dog.speak() === "Oddie barks.")
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-import-02.js b/tests/jerry/es2015/module-import-02.js
index 6b3d7da04e..669c7a49e6 100644
--- a/tests/jerry/es2015/module-import-02.js
+++ b/tests/jerry/es2015/module-import-02.js
@@ -22,6 +22,3 @@ assert (b_ === 5)
 assert (c_(b_) === 10)
 assert (mod.x === 42)
 assert (Array.isArray(mod.d))
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-import-03.js b/tests/jerry/es2015/module-import-03.js
index 49cd5e989d..11214a9e62 100644
--- a/tests/jerry/es2015/module-import-03.js
+++ b/tests/jerry/es2015/module-import-03.js
@@ -22,6 +22,3 @@ assert(i.incr() === 6);
 assert (aa === "a");
 assert (x === 42);
 assert (c_(x) == 84);
-
-// Pre-scanner regression test
-for (var tmp in {}) ;
diff --git a/tests/jerry/es2015/module-import-04.js b/tests/jerry/es2015/module-import-04.js
index 91abdc34ad..f0a5181a1b 100644
--- a/tests/jerry/es2015/module-import-04.js
+++ b/tests/jerry/es2015/module-import-04.js
@@ -17,6 +17,3 @@ import "module-import-01.js";
 import "module-export-05.js";
 import "module-export-06.js";
 import "module-export-07.js";
-
-// Pre-scanner regression test
-for (var tmp in {}) ;