diff --git a/src/bootstrap/format.rs b/src/bootstrap/format.rs
index 615794958d087..ae72a42973cd1 100644
--- a/src/bootstrap/format.rs
+++ b/src/bootstrap/format.rs
@@ -218,7 +218,7 @@ pub fn format(build: &Builder<'_>, check: bool, paths: &[PathBuf]) {
                     WalkBuilder::new(first)
                 }
             } else {
-                WalkBuilder::new(first)
+                WalkBuilder::new(src.join(first))
             };
 
             for path in &paths[1..] {
@@ -229,7 +229,7 @@ pub fn format(build: &Builder<'_>, check: bool, paths: &[PathBuf]) {
                         walker.add(path);
                     }
                 } else {
-                    walker.add(path);
+                    walker.add(src.join(path));
                 }
             }