diff --git a/clean.sh b/clean.sh
index e157121e1..101cbdc87 100755
--- a/clean.sh
+++ b/clean.sh
@@ -32,7 +32,7 @@ for d in tools-for-build; do
     $GNUMAKE -I ../src/runtime -s clean
     cd "$original_pwd" > /dev/null
 done
-( cd ./doc ; sh ./clean.sh )
+( cd ./doc && sh ./clean.sh )
 
 # Within all directories, remove things which don't look like source
 # files. Some explanations:
diff --git a/doc/clean.sh b/doc/clean.sh
index 5ed17ee65..023c29c2d 100644
--- a/doc/clean.sh
+++ b/doc/clean.sh
@@ -1,4 +1,4 @@
 #!/bin/sh
 
-(cd manual; sh clean.sh)
-(cd internals; sh clean.sh)
+(cd ./manual && sh ./clean.sh)
+(cd ./internals && sh ./clean.sh)