diff --git a/src/libcoreint/opcodes-ecma-relational.c b/src/libcoreint/opcodes-ecma-relational.c
index 79bc74e6a..157c85088 100644
--- a/src/libcoreint/opcodes-ecma-relational.c
+++ b/src/libcoreint/opcodes-ecma-relational.c
@@ -291,6 +291,8 @@ opfunc_in (opcode_t opdata __unused, /**< operation data */
   const idx_t left_var_idx = opdata.data.in.var_left;
   const idx_t right_var_idx = opdata.data.in.var_right;
 
+  int_data->pos++;
+
   ecma_completion_value_t ret_value;
 
   ECMA_TRY_CATCH (left_value, get_variable_value (int_data, left_var_idx, false), ret_value);