diff --git a/src/protocol/mod.rs b/src/protocol/mod.rs
index 993e4e64f949e0ff8efe028d9ccc4231b21c7d8d..d0dd2453c06c9f49d1cce7f935c3c0f092dba0ce 100644
--- a/src/protocol/mod.rs
+++ b/src/protocol/mod.rs
@@ -52,7 +52,7 @@ pub enum ComponentCreationError {
 impl ProtocolDescription {
     pub fn parse(buffer: &[u8]) -> Result<Self, String> {
         let source = InputSource::new(String::new(), Vec::from(buffer));
-        let mut parser = Parser::new()?;
+        let mut parser = Parser::new(None)?;
         parser.feed(source).expect("failed to feed source");
         
         if let Err(err) = parser.parse() {
@@ -253,10 +253,9 @@ pub struct ProtocolDescriptionBuilder {
 }
 
 impl ProtocolDescriptionBuilder {
-    pub fn new() -> Result<Self, String> {
-        return Ok(Self{
-            parser: Parser::new()?,
-        })
+    pub fn new(std_lib_dir: Option<String>) -> Result<Self, String> {
+        let mut parser = Parser::new(std_lib_dir)?;
+        return Ok(Self{ parser })
     }
 
     pub fn add(&mut self, filename: String, buffer: Vec<u8>) -> Result<(), ParseError> {