diff --git a/src/librustc/session/mod.rs b/src/librustc/session/mod.rs
index 42c633dc83fe5..c87881341daa2 100644
--- a/src/librustc/session/mod.rs
+++ b/src/librustc/session/mod.rs
@@ -776,7 +776,12 @@ pub fn build_session_(sopts: config::Options,
     let print_fuel_crate = sopts.debugging_opts.print_fuel.clone();
     let print_fuel = Cell::new(0);
 
-    let working_dir = env::current_dir().unwrap().to_string_lossy().into_owned();
+    let working_dir = match env::current_dir() {
+        Ok(dir) => dir.to_string_lossy().into_owned(),
+        Err(e) => {
+            panic!(p_s.span_diagnostic.fatal(&format!("Current directory is invalid: {}", e)))
+        }
+    };
     let working_dir = file_path_mapping.map_prefix(working_dir);
 
     let sess = Session {