diff --git a/stdlib/src/pdf.rs b/stdlib/src/pdf.rs
index 1b9fe676..c2af223e 100644
--- a/stdlib/src/pdf.rs
+++ b/stdlib/src/pdf.rs
@@ -19,3 +19,21 @@ impl StdlibRegistry {
         );
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_register_pdf() {
+        let mut registry = StdlibRegistry::default();
+        registry.register_pdf();
+
+        assert!(registry.has_module("std.pdf"));
+        let module = registry.get_module("std.pdf").unwrap();
+        assert_eq!(module.name, "std.pdf");
+        assert_eq!(module.version, "1.0.0");
+        assert!(module.exports.is_empty());
+        assert!(module.required_capabilities.is_empty());
+    }
+}