diff --git a/src/build.rs b/src/build.rs
index 267183d..7c89139 100644
--- a/src/build.rs
+++ b/src/build.rs
@@ -102,17 +102,21 @@ pub fn build(
 		)?;
 	}
 
-	if has_ctor(&ctor_module, target_runtime) {
-		if !skip_optimization {
-			optimize(&mut ctor_module, vec![target_runtime.symbols().create])?;
-		}
-		let ctor_module = pack_instance(
+	if !has_ctor(&ctor_module, target_runtime) {
+		return Ok((module, None))
+	}
+
+	if !skip_optimization {
+		optimize(&mut ctor_module, vec![target_runtime.symbols().create])?;
+	}
+
+	if let TargetRuntime::PWasm(_) = target_runtime {
+		ctor_module = pack_instance(
 			parity_wasm::serialize(module.clone()).map_err(Error::Encoding)?,
 			ctor_module.clone(),
 			target_runtime,
 		)?;
-		Ok((module, Some(ctor_module)))
-	} else {
-		Ok((module, None))
 	}
+
+	Ok((module, Some(ctor_module)))
 }
diff --git a/src/pack.rs b/src/pack.rs
index f318925..b2d6c03 100644
--- a/src/pack.rs
+++ b/src/pack.rs
@@ -195,10 +195,6 @@ pub fn pack_instance(raw_module: Vec<u8>, mut ctor_module: elements::Module, tar
             ])).build()
             .build()
         .build();
-    
-    if let TargetRuntime::Substrate(_) = target {
-        return Ok(new_module)
-    }
 
     for section in new_module.sections_mut() {
         if let &mut Section::Export(ref mut export_section) = section {