diff --git a/src/libcoreint/interpreter.c b/src/libcoreint/interpreter.c
index 376835082..c109e706a 100644
--- a/src/libcoreint/interpreter.c
+++ b/src/libcoreint/interpreter.c
@@ -46,7 +46,7 @@ run_int (void)
 {
   JERRY_ASSERT( __program != NULL );
 
-  const op_idx_t start_pos = 0;
+  const opcode_counter_t start_pos = 0;
   ecma_value_t this_binding_value = ecma_make_simple_value( ECMA_SIMPLE_VALUE_UNDEFINED);
   ecma_object_t *lex_env_p = ecma_create_lexical_environment (NULL,
                                                               ECMA_LEXICAL_ENVIRONMENT_DECLARATIVE);
@@ -88,7 +88,7 @@ run_int (void)
 }
 
 ecma_completion_value_t
-run_int_from_pos (op_idx_t start_pos,
+run_int_from_pos (opcode_counter_t start_pos,
                   ecma_value_t this_binding_value,
                   ecma_object_t *lex_env_p,
                   bool is_strict)
@@ -111,7 +111,7 @@ run_int_from_pos (op_idx_t start_pos,
   JERRY_ASSERT( ecma_is_value_empty( regs[0]) );
 
   struct __int_data int_data;
-  int_data.pos = (op_idx_t) (start_pos + 1);
+  int_data.pos = (opcode_counter_t) (start_pos + 1);
   int_data.this_binding = this_binding_value;
   int_data.lex_env_p = lex_env_p;
   int_data.is_strict = is_strict;
diff --git a/src/libcoreint/interpreter.h b/src/libcoreint/interpreter.h
index 5ee8c0550..c1d22f544 100644
--- a/src/libcoreint/interpreter.h
+++ b/src/libcoreint/interpreter.h
@@ -20,11 +20,11 @@
 #include "globals.h"
 #include "opcodes.h"
 
-typedef uint16_t op_idx_t;
+typedef uint16_t opcode_counter_t;
 
 struct __int_data
 {
-  op_idx_t pos; /**< current opcode to execute */
+  opcode_counter_t pos; /**< current opcode to execute */
   ecma_value_t this_binding; /**< this binding for current context */
   ecma_object_t *lex_env_p; /**< current lexical environment */
   bool is_strict; /**< is current code execution mode strict? */
@@ -35,7 +35,7 @@ struct __int_data
 
 void init_int (const OPCODE* program_p);
 bool run_int (void);
-ecma_completion_value_t run_int_from_pos (op_idx_t start_pos,
+ecma_completion_value_t run_int_from_pos (opcode_counter_t start_pos,
                                           ecma_value_t this_binding_value,
                                           ecma_object_t *lex_env_p,
                                           bool is_strict);
diff --git a/src/libcoreint/opcodes.c b/src/libcoreint/opcodes.c
index 3fbf70745..f831d88da 100644
--- a/src/libcoreint/opcodes.c
+++ b/src/libcoreint/opcodes.c
@@ -565,7 +565,7 @@ opfunc_jmp_down (OPCODE opdata, /**< operation data */
 {
   JERRY_ASSERT( int_data->pos <= int_data->pos + opdata.data.jmp_up.opcode_count );
 
-  int_data->pos = (op_idx_t) ( int_data->pos + opdata.data.jmp_down.opcode_count );
+  int_data->pos = (opcode_counter_t) ( int_data->pos + opdata.data.jmp_down.opcode_count );
 
   return ecma_make_empty_completion_value();
 } /* opfunc_jmp_down */
@@ -582,7 +582,7 @@ opfunc_jmp_up (OPCODE opdata, /**< operation data */
 {
   JERRY_ASSERT( int_data->pos >= opdata.data.jmp_up.opcode_count );
 
-  int_data->pos = (op_idx_t) ( int_data->pos - opdata.data.jmp_down.opcode_count );
+  int_data->pos = (opcode_counter_t) ( int_data->pos - opdata.data.jmp_down.opcode_count );
 
   return ecma_make_empty_completion_value();
 } /* opfunc_jmp_up */
@@ -1309,16 +1309,16 @@ opfunc_func_decl_0(OPCODE opdata, /**< operation data */
 
   const bool is_strict = int_data->is_strict;
 
-  const op_idx_t varg_first_opcode_idx = (op_idx_t) (int_data->pos + 1);
+  const opcode_counter_t varg_first_opcode_idx = (opcode_counter_t) (int_data->pos + 1);
   int_data->pos = varg_first_opcode_idx;
 
   TODO( Iterate vargs );
 
-  const op_idx_t jmp_down_opcode_idx = (op_idx_t) (int_data->pos);
+  const opcode_counter_t jmp_down_opcode_idx = (opcode_counter_t) (int_data->pos);
 
   TODO( ASSERT( Current opcode is jmp_down ) );
 
-  const op_idx_t function_code_opcode_idx = (op_idx_t) (jmp_down_opcode_idx + 1);
+  const opcode_counter_t function_code_opcode_idx = (opcode_counter_t) (jmp_down_opcode_idx + 1);
 
   // a.
   const ecma_char_t *fn = function_name.str_p;
diff --git a/src/libecmaoperations/ecma-function-object.c b/src/libecmaoperations/ecma-function-object.c
index 838f8de66..ba0cc4d73 100644
--- a/src/libecmaoperations/ecma-function-object.c
+++ b/src/libecmaoperations/ecma-function-object.c
@@ -37,7 +37,7 @@
  */
 static uint32_t
 ecma_pack_code_internal_property_value( bool is_strict, /**< is code strict? */
-                                        op_idx_t opcode_idx) /**< index of first opcode */
+                                        opcode_counter_t opcode_idx) /**< index of first opcode */
 {
   uint32_t value = opcode_idx;
   const uint32_t is_strict_bit_offset = sizeof(value) * JERRY_BITSINBYTE - 1;
@@ -58,7 +58,7 @@ ecma_pack_code_internal_property_value( bool is_strict, /**< is code strict? */
  *
  * @return opcode index
  */
-static op_idx_t
+static opcode_counter_t
 ecma_unpack_code_internal_property_value( uint32_t value, /**< packed value */
                                           bool* out_is_strict_p) /**< out: is code strict? */
 {
@@ -69,7 +69,7 @@ ecma_unpack_code_internal_property_value( uint32_t value, /**< packed value */
   bool is_strict = ( ( value & ( 1u << is_strict_bit_offset ) ) != 0 );
   *out_is_strict_p = is_strict;
 
-  op_idx_t opcode_idx = (op_idx_t) ( value & ~( 1u << is_strict_bit_offset ) );
+  opcode_counter_t opcode_idx = (opcode_counter_t) ( value & ~( 1u << is_strict_bit_offset ) );
 
   return opcode_idx;
 } /* ecma_unpack_code_internal_property_value */
@@ -111,7 +111,7 @@ ecma_op_create_function_object( const ecma_char_t* formal_parameter_list_p[], /*
                                 size_t formal_parameters_number, /**< formal parameters list's length */
                                 ecma_object_t *scope_p, /**< function's scope */
                                 bool is_strict, /**< 'strict' flag */
-                                op_idx_t first_opcode_idx) /**< index of first opcode of function's body */
+                                opcode_counter_t first_opcode_idx) /**< index of first opcode of function's body */
 {
   // 1., 4., 13.
   FIXME( Setup prototype of Function object to built-in Function prototype object (15.3.3.1) );
@@ -262,7 +262,7 @@ ecma_op_function_call( ecma_object_t *func_obj_p, /**< Function object */
 
       bool is_strict;
       // 8.
-      op_idx_t code_first_opcode_idx = ecma_unpack_code_internal_property_value( code_prop_value, &is_strict);
+      opcode_counter_t code_first_opcode_idx = ecma_unpack_code_internal_property_value( code_prop_value, &is_strict);
 
       ecma_value_t this_binding;
       // 1.
diff --git a/src/libecmaoperations/ecma-function-object.h b/src/libecmaoperations/ecma-function-object.h
index 2e9b728a4..53e527c0a 100644
--- a/src/libecmaoperations/ecma-function-object.h
+++ b/src/libecmaoperations/ecma-function-object.h
@@ -33,7 +33,7 @@ ecma_op_create_function_object( const ecma_char_t* formal_parameter_list_p[],
                                 size_t formal_parameters_number,
                                 ecma_object_t *scope_p,
                                 bool is_strict,
-                                op_idx_t first_opcode_idx);
+                                opcode_counter_t first_opcode_idx);
 
 extern ecma_object_t* ecma_op_get_throw_type_error( void);