diff --git a/core/extensions/impl/storage_extension.cpp b/core/extensions/impl/storage_extension.cpp
index 5fa42c19fd..45ed90b29c 100644
--- a/core/extensions/impl/storage_extension.cpp
+++ b/core/extensions/impl/storage_extension.cpp
@@ -126,17 +126,16 @@ namespace kagome::extensions {
       runtime::WasmSpan key_pos,
       runtime::WasmSpan value_out,
       runtime::WasmOffset offset) {
-    static constexpr runtime::WasmSpan kErrorSpan = -1;
-
     auto [key_ptr, key_size] = runtime::WasmResult(key_pos);
     auto [value_ptr, value_size] = runtime::WasmResult(value_out);
 
     auto key = memory_->loadN(key_ptr, key_size);
+    boost::optional<uint32_t> res{boost::none};
     if (auto data = get(key, offset, value_size)) {
       memory_->storeBuffer(value_ptr, data.value());
-      return runtime::WasmResult(0, data.value().size()).combine();
+      res = value_size;
     }
-    return kErrorSpan;
+    return memory_->storeBuffer(scale::encode(res).value());
   }
 
   void StorageExtension::ext_set_storage(const runtime::WasmPointer key_data,
diff --git a/test/core/extensions/storage_extension_test.cpp b/test/core/extensions/storage_extension_test.cpp
index 4c45f305e7..480b1cd4b0 100644
--- a/test/core/extensions/storage_extension_test.cpp
+++ b/test/core/extensions/storage_extension_test.cpp
@@ -437,6 +437,8 @@ TEST_P(OutcomeParameterizedTest, StorageReadTest) {
   WasmResult value(42, 41);
   Buffer value_data(8, 'v');
   WasmOffset offset = 0;
+  EXPECT_OUTCOME_TRUE(encoded_opt_val_size, kagome::scale::encode(boost::make_optional(value.length)));
+  WasmSpan res_wasm_span = 1337;
 
   // expect key loaded, than data stored
   EXPECT_CALL(*memory_, loadN(key.address, key.length))
@@ -446,9 +448,13 @@ TEST_P(OutcomeParameterizedTest, StorageReadTest) {
   EXPECT_CALL(*trie_batch_, get(key_data)).WillOnce(Return(value_data));
   EXPECT_CALL(*memory_,
               storeBuffer(value.address, gsl::span<const uint8_t>(value_data)));
+  EXPECT_CALL(*memory_,
+              storeBuffer(gsl::span<const uint8_t>(encoded_opt_val_size)))
+      .WillOnce(Return(res_wasm_span));
 
-  storage_extension_->ext_storage_read_version_1(
-      key.combine(), value.combine(), offset);
+  ASSERT_EQ(res_wasm_span,
+            storage_extension_->ext_storage_read_version_1(
+                key.combine(), value.combine(), offset));
 }
 
 INSTANTIATE_TEST_CASE_P(Instance,