diff -r 6dc91e602dea .classpath
--- a/.classpath	Mon Apr 16 08:42:47 2012 -0700
+++ b/.classpath	Wed Apr 18 15:19:48 2012 +0100
@@ -38,5 +38,6 @@
 	<classpathentry kind="lib" path="extlibs/jffi.jar"/>
 	<classpathentry kind="lib" path="extlibs/jnr-posix.jar"/>
 	<classpathentry kind="lib" path="extlibs/guava-r07.jar"/>
+	<classpathentry kind="var" path="ANT_HOME"/>
 	<classpathentry kind="output" path="build/classes"/>
 </classpath>
diff -r 6dc91e602dea src/org/python/core/PyString.java
--- a/src/org/python/core/PyString.java	Mon Apr 16 08:42:47 2012 -0700
+++ b/src/org/python/core/PyString.java	Wed Apr 18 15:19:48 2012 +0100
@@ -2,6 +2,7 @@
 package org.python.core;
 
 import java.math.BigInteger;
+import java.util.Locale;
 
 import org.python.core.util.ExtraMath;
 import org.python.core.util.StringUtil;
@@ -924,7 +925,7 @@
     
     @ExposedMethod(doc = BuiltinDocs.str_lower_doc)
     final String str_lower() {
-        return getString().toLowerCase();
+        return getString().toLowerCase(Locale.ENGLISH);
     }
 
     public String upper() {
@@ -933,7 +934,7 @@
 
     @ExposedMethod(doc = BuiltinDocs.str_upper_doc)
     final String str_upper() {
-        return getString().toUpperCase();
+        return getString().toUpperCase(Locale.ENGLISH);
     }
 
     public String title() {
diff -r 6dc91e602dea src/org/python/modules/posix/OS.java
--- a/src/org/python/modules/posix/OS.java	Mon Apr 16 08:42:47 2012 -0700
+++ b/src/org/python/modules/posix/OS.java	Wed Apr 18 15:19:48 2012 +0100
@@ -1,6 +1,8 @@
 /* Copyright (c) Jython Developers */
 package org.python.modules.posix;
 
+import java.util.Locale;
+
 import org.python.core.PySystemState;
 
 /**
@@ -30,7 +32,7 @@
     }
 
     String getModuleName() {
-        return name().toLowerCase();
+        return name().toLowerCase(Locale.ENGLISH);
     }
 
     String[][] getShellCommands() {