diff --git a/build/src/main.rs b/build/src/main.rs
index a95cefe..3f6adb6 100644
--- a/build/src/main.rs
+++ b/build/src/main.rs
@@ -71,8 +71,8 @@ fn main() {
 		.arg(Arg::with_name("skip_optimization")
 			.help("Skip symbol optimization step producing final wasm")
 			.long("skip-optimization"))
-		.arg(Arg::with_name("skip_alloc")
-			.help("Skip allocator externalizer step producing final wasm")
+		.arg(Arg::with_name("skip_externalize")
+			.help("Skip externalizer step producing final wasm")
 			.long("skip-externalize"))
 		.arg(Arg::with_name("runtime_type")
 			.help("Injects RUNTIME_TYPE global export")
@@ -93,10 +93,10 @@ fn main() {
 
 	let mut module = parity_wasm::deserialize_file(&path).unwrap();
 
-	if !matches.is_present("skip_alloc") {
+	if !matches.is_present("skip_externalize") {
 		module = wasm_utils::externalize(
 			module,
-			vec!["_free", "_malloc"],
+			vec!["_free", "_malloc", "_memcpy", "_memset", "_memmove"],
 		);
 	}
 
diff --git a/ext/src/main.rs b/ext/src/main.rs
index 99c7e22..6904d24 100644
--- a/ext/src/main.rs
+++ b/ext/src/main.rs
@@ -14,8 +14,8 @@ fn main() {
 	}
 
 	let module = wasm_utils::externalize(
-		parity_wasm::deserialize_file(&args[1]).expect("Module to deserialize ok"), 
-		vec!["_free", "_malloc"],
+		parity_wasm::deserialize_file(&args[1]).expect("Module to deserialize ok"),
+		vec!["_free", "_malloc", "_memcpy", "_memset", "_memmove"],
 	);
 
 	parity_wasm::serialize_to_file(&args[2], module).expect("Module to serialize ok");