diff --git a/rust-runner/src/alloc.rs b/rust-runner/src/alloc.rs
index bd17625..ffb29cf 100644
--- a/rust-runner/src/alloc.rs
+++ b/rust-runner/src/alloc.rs
@@ -8,8 +8,7 @@ pub struct Error;
 
 impl Arena {
     pub fn new(stack_top: u32) -> Self {
-        MemoryArenaAllocator {
-            module: module,
+        Arena {
             dynamic_top: stack_top,
         }
     }
diff --git a/rust-runner/src/main.rs b/rust-runner/src/main.rs
index 9b845dc..22940fb 100644
--- a/rust-runner/src/main.rs
+++ b/rust-runner/src/main.rs
@@ -11,10 +11,10 @@ mod alloc;
 mod storage;
 
 use std::env;
+use parity_wasm::interpreter::ModuleInstanceInterface;
 
 fn main() {
-    /// First, load wasm contract as a module
-
+    // First, load wasm contract as a module
     wasm_utils::init_log();
 
     let args = env::args().collect::<Vec<_>>();
@@ -25,17 +25,17 @@ fn main() {
 
     let module = parity_wasm::deserialize_file(&args[1]).expect("Module deserialization to succeed");
 
-    /// Second, create program instance
+    // Second, create program instance
     let program = parity_wasm::interpreter::ProgramInstance::new().expect("Program instance to be created");
 
-    /// Add module to the programm
-    program.add_module("contract", module);
+    // Add module to the programm
+    let module_instance = program.add_module("contract", module).expect("Module to be added successfully");
 
-    /// Create allocator
+    // Create allocator
     let mut allocator = alloc::Arena::new(5*1024*1024);
 
+    // Invoke _call method of the module
+    module_instance.execute_export("_call", vec![]).expect("_call to execute successfully");
 
-    /// Invoke _call method of the module
-
-    /// ???
+    // ???
 }
\ No newline at end of file
diff --git a/rust-runner/src/storage.rs b/rust-runner/src/storage.rs
index 0ead7b4..70412f2 100644
--- a/rust-runner/src/storage.rs
+++ b/rust-runner/src/storage.rs
@@ -2,7 +2,7 @@ use parity_wasm::interpreter::ModuleInstanceInterface;
 use parity_wasm::interpreter::ItemIndex;
 use std::sync::Arc;
 
-const DEFAULT_MEMORY_INDEX: ItemIndex = ItemIndex(0);
+const DEFAULT_MEMORY_INDEX: ItemIndex = ItemIndex::Internal(0);
 
 pub struct Storage {
     data: Vec<u8>,
@@ -21,7 +21,7 @@ impl Storage {
 
         match memory.set(dst, &self.data[offset as usize..offset as usize + len as usize]) {
             Err(_) => { return -1; }
-            Ok(_) => return len;
+            Ok(_) => { return len as i32; }
         }
     }
 
@@ -33,16 +33,18 @@ impl Storage {
 
         let slice = match memory.get(src, len as usize) {
             Err(_) => { return -1; }
-            Ok(slice) => return slice;
+            Ok(slice) => slice,
         };
 
-        if self.data.len() < offset as usize + slice.len {
-            self.data.reserve(offset as usize + slice.len);
+        if self.data.len() < offset as usize + slice.len() {
+            self.data.reserve(offset as usize + slice.len());
             unsafe {
-                self.data.set_len(offset as usize + slice.len);
+                self.data.set_len(offset as usize + slice.len());
             }
         }
-        self.data[offset as usize..offset as usize + slice.len].copy_from_slice(&slice[..]);
+        self.data[offset as usize..offset as usize + slice.len()].copy_from_slice(&slice[..]);
+
+        slice.len() as i32
     }
 
     pub fn size(&self) -> u32 { self.data.len() as u32 }