diff --git a/core/src/test/java/hudson/FunctionsTest.java b/core/src/test/java/hudson/FunctionsTest.java
index 349811e0c2..614a23ad56 100644
--- a/core/src/test/java/hudson/FunctionsTest.java
+++ b/core/src/test/java/hudson/FunctionsTest.java
@@ -23,8 +23,7 @@
  */
 package hudson;
 
-import java.text.DecimalFormat;
-import java.text.DecimalFormatSymbols;
+import java.util.Locale;
 
 import hudson.model.Action;
 import static org.junit.Assert.*;
@@ -123,18 +122,21 @@ public class FunctionsTest {
 
     @Test
     @Bug(16630)
-    public void testhumanReadableFileSize(){
-        DecimalFormat format = (DecimalFormat) DecimalFormat.getInstance();
-        DecimalFormatSymbols symbols = format.getDecimalFormatSymbols();
-        char sep = symbols.getDecimalSeparator();
-        assertEquals("0 B", Functions.humanReadableByteSize(0));
-        assertEquals("1023 B", Functions.humanReadableByteSize(1023));
-        assertEquals("1"+sep+"00 KB", Functions.humanReadableByteSize(1024));
-        assertEquals("1"+sep+"50 KB", Functions.humanReadableByteSize(1536));
-        assertEquals("20"+sep+"00 KB", Functions.humanReadableByteSize(20480));
-        assertEquals("1023"+sep+"00 KB", Functions.humanReadableByteSize(1047552));
-        assertEquals("1"+sep+"00 MB", Functions.humanReadableByteSize(1048576));
-        assertEquals("1"+sep+"50 GB", Functions.humanReadableByteSize(1610612700));
+    public void testHumanReadableFileSize(){
+        Locale defaultLocale = Locale.getDefault();
+        try{
+            Locale.setDefault(Locale.ENGLISH);
+            assertEquals("0 B", Functions.humanReadableByteSize(0));
+            assertEquals("1023 B", Functions.humanReadableByteSize(1023));
+            assertEquals("1.00 KB", Functions.humanReadableByteSize(1024));
+            assertEquals("1.50 KB", Functions.humanReadableByteSize(1536));
+            assertEquals("20.00 KB", Functions.humanReadableByteSize(20480));
+            assertEquals("1023.00 KB", Functions.humanReadableByteSize(1047552));
+            assertEquals("1.00 MB", Functions.humanReadableByteSize(1048576));
+            assertEquals("1.50 GB", Functions.humanReadableByteSize(1610612700));
+        }finally{
+            Locale.setDefault(defaultLocale);
+        }
     }
 
 }