diff --git a/py/objarray.c b/py/objarray.c
index a17ae276e2..58285c8660 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -33,6 +33,7 @@
 #include "py/runtime0.h"
 #include "py/runtime.h"
 #include "py/binary.h"
+#include "py/objstr.h"
 
 #if MICROPY_PY_ARRAY || MICROPY_PY_BUILTINS_BYTEARRAY || MICROPY_PY_BUILTINS_MEMORYVIEW
 
@@ -283,6 +284,29 @@ STATIC mp_obj_t array_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in)
             return lhs_in;
         }
 
+        case MP_BINARY_OP_IN: {
+            /* NOTE `a in b` is `b.__contains__(a)` */
+            mp_buffer_info_t lhs_bufinfo;
+            mp_buffer_info_t rhs_bufinfo;
+
+            // Can search string only in bytearray
+            if (mp_get_buffer(rhs_in, &rhs_bufinfo, MP_BUFFER_READ)) {
+                if (!MP_OBJ_IS_TYPE(lhs_in, &mp_type_bytearray)) {
+                    return mp_const_false;
+                }
+                array_get_buffer(lhs_in, &lhs_bufinfo, MP_BUFFER_READ);
+                return mp_obj_new_bool(
+                    find_subbytes(lhs_bufinfo.buf, lhs_bufinfo.len, rhs_bufinfo.buf, rhs_bufinfo.len, 1) != NULL);
+            }
+
+            // Otherwise, can only look for a scalar numeric value in an array
+            if (MP_OBJ_IS_INT(rhs_in) || mp_obj_is_float(rhs_in)) {
+                mp_not_implemented("");
+            }
+
+            return mp_const_false;
+        }
+
         case MP_BINARY_OP_EQUAL: {
             mp_buffer_info_t lhs_bufinfo;
             mp_buffer_info_t rhs_bufinfo;
diff --git a/py/objstr.c b/py/objstr.c
index 60f65d8439..0c2d904035 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -245,7 +245,7 @@ wrong_args:
 
 // like strstr but with specified length and allows \0 bytes
 // TODO replace with something more efficient/standard
-STATIC const byte *find_subbytes(const byte *haystack, mp_uint_t hlen, const byte *needle, mp_uint_t nlen, mp_int_t direction) {
+const byte *find_subbytes(const byte *haystack, mp_uint_t hlen, const byte *needle, mp_uint_t nlen, mp_int_t direction) {
     if (hlen >= nlen) {
         mp_uint_t str_index, str_index_end;
         if (direction > 0) {
diff --git a/py/objstr.h b/py/objstr.h
index 6179a74afc..6b8ad97ec2 100644
--- a/py/objstr.h
+++ b/py/objstr.h
@@ -71,6 +71,7 @@ mp_int_t mp_obj_str_get_buffer(mp_obj_t self_in, mp_buffer_info_t *bufinfo, mp_u
 
 const byte *str_index_to_ptr(const mp_obj_type_t *type, const byte *self_data, size_t self_len,
                              mp_obj_t index, bool is_slice);
+const byte *find_subbytes(const byte *haystack, mp_uint_t hlen, const byte *needle, mp_uint_t nlen, mp_int_t direction);
 
 MP_DECLARE_CONST_FUN_OBJ(str_encode_obj);
 MP_DECLARE_CONST_FUN_OBJ(str_find_obj);