diff --git a/jerry-core/ecma/base/ecma-helpers.cpp b/jerry-core/ecma/base/ecma-helpers.cpp
index e30385d19..3ff849e13 100644
--- a/jerry-core/ecma/base/ecma-helpers.cpp
+++ b/jerry-core/ecma/base/ecma-helpers.cpp
@@ -829,8 +829,12 @@ ecma_free_internal_property (ecma_property_t *property_p) /**< the property */
     }
     case ECMA_INTERNAL_PROPERTY_REGEXP_BYTECODE:
     {
-      void *bytecode_p = ECMA_GET_NON_NULL_POINTER (void, property_value);
-      mem_heap_free_block (bytecode_p);
+      void *bytecode_p = ECMA_GET_POINTER (void, property_value);
+
+      if (bytecode_p)
+      {
+        mem_heap_free_block (bytecode_p);
+      }
     }
   }
 
diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-regexp-prototype.cpp b/jerry-core/ecma/builtin-objects/ecma-builtin-regexp-prototype.cpp
index ee4b205ef..2afe5a8df 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-regexp-prototype.cpp
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-regexp-prototype.cpp
@@ -15,6 +15,7 @@
  */
 
 #include "ecma-alloc.h"
+#include "ecma-array-object.h"
 #include "ecma-builtins.h"
 #include "ecma-conversion.h"
 #include "ecma-exceptions.h"
@@ -72,7 +73,44 @@ ecma_builtin_regexp_prototype_exec (ecma_value_t this_arg, /**< this argument */
                     ecma_op_to_string (arg),
                     ret_value);
 
-    ret_value = ecma_regexp_exec_helper (obj_this, input_str_value, false);
+    ecma_property_t *bytecode_prop_p;
+    ecma_object_t *obj_p = ecma_get_object_from_completion_value (obj_this);
+    bytecode_prop_p = ecma_get_internal_property (obj_p, ECMA_INTERNAL_PROPERTY_REGEXP_BYTECODE);
+
+    void *bytecode_p = ECMA_GET_POINTER (void, bytecode_prop_p->u.internal_property.value);
+
+    if (bytecode_p == NULL)
+    {
+      /* Missing bytecode means empty RegExp: '/(?:)/', so always return empty string. */
+      ecma_completion_value_t result_array = ecma_op_create_array_object (0, 0, false);
+      ecma_object_t *result_array_obj_p = ecma_get_object_from_completion_value (result_array);
+      ecma_string_t *input_str_p = ecma_get_string_from_value (input_str_value);
+      re_set_result_array_properties (result_array_obj_p,
+                                      input_str_p,
+                                      1,
+                                      0);
+
+      ecma_string_t *index_str_p = ecma_new_ecma_string_from_uint32 (0);
+      ecma_string_t *capture_str_p = ecma_get_magic_string (LIT_MAGIC_STRING__EMPTY);
+
+      ECMA_TRY_CATCH (put_res_value,
+                      ecma_op_object_put (result_array_obj_p,
+                                          index_str_p,
+                                          ecma_make_string_value (capture_str_p),
+                                          true),
+                      ret_value);
+
+      ret_value = result_array;
+
+      ECMA_FINALIZE (put_res_value)
+
+      ecma_deref_ecma_string (capture_str_p);
+      ecma_deref_ecma_string (index_str_p);
+    }
+    else
+    {
+      ret_value = ecma_regexp_exec_helper (obj_this, input_str_value, false);
+    }
 
     ECMA_FINALIZE (input_str_value);
     ECMA_FINALIZE (obj_this);
diff --git a/jerry-core/ecma/builtin-objects/ecma-builtins.cpp b/jerry-core/ecma/builtin-objects/ecma-builtins.cpp
index 62be3f2fb..711e177bf 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtins.cpp
+++ b/jerry-core/ecma/builtin-objects/ecma-builtins.cpp
@@ -167,8 +167,18 @@ ecma_builtin_init_object (ecma_builtin_id_t obj_builtin_id, /**< built-in ID */
       ECMA_SET_POINTER (prim_value_prop_p->u.internal_property.value, prim_prop_num_value_p);
       break;
     }
-#endif /* CONFIG_ECMA_COMPACT_PROFILE_DISABLE_DATE_BUILTIN */
+#endif /* !CONFIG_ECMA_COMPACT_PROFILE_DISABLE_DATE_BUILTIN */
 
+#ifndef CONFIG_ECMA_COMPACT_PROFILE_DISABLE_REGEXP_BUILTIN
+    case ECMA_BUILTIN_ID_REGEXP_PROTOTYPE:
+    {
+      ecma_property_t *bytecode_prop_p;
+      bytecode_prop_p = ecma_create_internal_property (object_obj_p,
+                                                       ECMA_INTERNAL_PROPERTY_REGEXP_BYTECODE);
+      bytecode_prop_p->u.internal_property.value = ECMA_NULL_POINTER;
+      break;
+    }
+#endif /* !CONFIG_ECMA_COMPACT_PROFILE_DISABLE_REGEXP_BUILTIN */
     default:
     {
       break;
diff --git a/jerry-core/ecma/operations/ecma-regexp-object.cpp b/jerry-core/ecma/operations/ecma-regexp-object.cpp
index b22dce876..78dd9ff2d 100644
--- a/jerry-core/ecma/operations/ecma-regexp-object.cpp
+++ b/jerry-core/ecma/operations/ecma-regexp-object.cpp
@@ -207,10 +207,11 @@ ecma_op_create_regexp_object (ecma_string_t *pattern_p, /**< input pattern */
   ecma_dealloc_number (lastindex_num_p);
 
   /* Set bytecode internal property. */
-  ecma_property_t *bytecode = ecma_create_internal_property (obj_p, ECMA_INTERNAL_PROPERTY_REGEXP_BYTECODE);
+  ecma_property_t *bytecode_prop_p;
+  bytecode_prop_p = ecma_create_internal_property (obj_p, ECMA_INTERNAL_PROPERTY_REGEXP_BYTECODE);
 
   /* Compile bytecode. */
-  ECMA_TRY_CATCH (empty, re_compile_bytecode (bytecode, pattern_p, flags), ret_value);
+  ECMA_TRY_CATCH (empty, re_compile_bytecode (bytecode_prop_p, pattern_p, flags), ret_value);
   ret_value = ecma_make_normal_completion_value (ecma_make_object_value (obj_p));
   ECMA_FINALIZE (empty);
 
@@ -1071,9 +1072,10 @@ re_match_regexp (re_matcher_ctx_t *re_ctx_p, /**< RegExp matcher context */
 /**
  * Define the necessary properties for the result array (index, input, length).
  */
-static void
+void
 re_set_result_array_properties (ecma_object_t *array_obj_p, /**< result array */
-                                re_matcher_ctx_t *re_ctx_p, /**< RegExp matcher context */
+                                ecma_string_t *input_str_p, /**< input string */
+                                uint32_t num_of_elements, /**< Number of array elements */
                                 int32_t index) /** index of matching */
 {
   /* Set index property of the result array */
@@ -1111,9 +1113,6 @@ re_set_result_array_properties (ecma_object_t *array_obj_p, /**< result array */
     ecma_property_descriptor_t array_item_prop_desc = ecma_make_empty_property_descriptor ();
 
     array_item_prop_desc.is_value_defined = true;
-    ecma_string_t *input_str_p = ecma_new_ecma_string_from_utf8 (re_ctx_p->input_start_p,
-                                                                 (lit_utf8_size_t) (re_ctx_p->input_end_p -
-                                                                                    re_ctx_p->input_start_p));
     array_item_prop_desc.value = ecma_make_string_value (input_str_p);
 
     array_item_prop_desc.is_writable_defined = true;
@@ -1129,8 +1128,6 @@ re_set_result_array_properties (ecma_object_t *array_obj_p, /**< result array */
                                         result_prop_str_p,
                                         &array_item_prop_desc,
                                         true);
-
-    ecma_deref_ecma_string (input_str_p);
   }
   ecma_deref_ecma_string (result_prop_str_p);
 
@@ -1142,7 +1139,7 @@ re_set_result_array_properties (ecma_object_t *array_obj_p, /**< result array */
     array_item_prop_desc.is_value_defined = true;
 
     ecma_number_t *num_p = ecma_alloc_number ();
-    *num_p = (ecma_number_t) (re_ctx_p->num_of_captures / 2);
+    *num_p = (ecma_number_t) (num_of_elements);
     array_item_prop_desc.value = ecma_make_number_value (num_p);
 
     array_item_prop_desc.is_writable_defined = false;
@@ -1315,7 +1312,9 @@ ecma_regexp_exec_helper (ecma_value_t regexp_value, /**< RegExp object */
       ecma_completion_value_t result_array = ecma_op_create_array_object (0, 0, false);
       ecma_object_t *result_array_obj_p = ecma_get_object_from_completion_value (result_array);
 
-      re_set_result_array_properties (result_array_obj_p, &re_ctx, index);
+      ecma_string_t *input_str_p = ecma_new_ecma_string_from_utf8 (iterator.buf_p, iterator.buf_size);
+      re_set_result_array_properties (result_array_obj_p, input_str_p, re_ctx.num_of_captures / 2, index);
+      ecma_deref_ecma_string (input_str_p);
 
       for (uint32_t i = 0; i < re_ctx.num_of_captures; i += 2)
       {
diff --git a/jerry-core/ecma/operations/ecma-regexp-object.h b/jerry-core/ecma/operations/ecma-regexp-object.h
index 6d86daad4..c06ca8351 100644
--- a/jerry-core/ecma/operations/ecma-regexp-object.h
+++ b/jerry-core/ecma/operations/ecma-regexp-object.h
@@ -59,6 +59,11 @@ ecma_regexp_exec_helper (ecma_value_t, ecma_value_t, bool);
 extern ecma_char_t
 re_canonicalize (ecma_char_t ch,
                  bool is_ignorecase);
+extern void
+re_set_result_array_properties (ecma_object_t *array_obj_p,
+                                ecma_string_t *input_str_p,
+                                uint32_t num_of_elements,
+                                int32_t index);
 
 /**
  * @}
diff --git a/tests/jerry/regression-test-issue-312.js b/tests/jerry/regression-test-issue-312.js
new file mode 100644
index 000000000..a3f063f4d
--- /dev/null
+++ b/tests/jerry/regression-test-issue-312.js
@@ -0,0 +1,21 @@
+// Copyright 2015 Samsung Electronics Co., Ltd.
+// Copyright 2015 University of Szeged.
+//
+// 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.
+
+var res = RegExp.prototype.exec(10);
+
+assert (res[0] === "");
+assert (res.input === "10");
+assert (res.index === 0);
+assert (res.length === 1);