diff --git a/algs4/.gitignore b/algs4/.gitignore
index e3e6f3d..7975420 100644
--- a/algs4/.gitignore
+++ b/algs4/.gitignore
@@ -6,3 +6,7 @@ drjava.jar
 findbugs-1.3.9/
 findbugs.zip
 stdlib.jar
+/largeT.txt
+/largeW.txt
+/tinyT.txt
+/tinyW.txt
diff --git a/algs4/extract-jars b/algs4/extract-jars
index f887701..055fb55 100755
--- a/algs4/extract-jars
+++ b/algs4/extract-jars
@@ -3,5 +3,7 @@
 set -e
 
 cd src/java
+chmod 644 *.java *.class *.jar
 jar xf ../../algs4.jar
 jar xf ../../stdlib.jar
+chmod 444 *.java *.class *.jar