diff --git a/src/session/builder/impl_options.rs b/src/session/builder/impl_options.rs
index 24a7f8d5..ee55935a 100644
--- a/src/session/builder/impl_options.rs
+++ b/src/session/builder/impl_options.rs
@@ -1,4 +1,10 @@
-use std::{borrow::Cow, ffi::c_char, path::Path, rc::Rc, sync::Arc};
+use std::{
+	borrow::Cow,
+	ffi::{CString, c_char},
+	path::Path,
+	rc::Rc,
+	sync::Arc
+};
 
 use super::SessionBuilder;
 use crate::{
@@ -139,9 +145,9 @@ impl SessionBuilder {
 	}
 
 	pub fn with_external_initializer(mut self, name: impl AsRef<str>, value: DynValue) -> Result<Self> {
-		let name = name.as_ref();
+		let name = CString::new(name.as_ref())?;
 		let value = Rc::new(value);
-		ortsys![unsafe AddExternalInitializers(self.session_options_ptr.as_ptr(), &name.as_ptr().cast::<c_char>(), &value.ptr().cast_const(), 1)?];
+		ortsys![unsafe AddExternalInitializers(self.session_options_ptr.as_ptr(), &name.as_ptr(), &value.ptr().cast_const(), 1)?];
 		self.external_initializers.push(value);
 		Ok(self)
 	}