diff --git a/src/zutil/net/smtp/Email.java b/src/zutil/net/smtp/Email.java
index 1376c28..1528949 100755
--- a/src/zutil/net/smtp/Email.java
+++ b/src/zutil/net/smtp/Email.java
@@ -4,6 +4,7 @@ import java.io.IOException;
 import java.io.Writer;
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.Locale;
 import java.util.regex.Pattern;
 
 import static zutil.net.smtp.SMTPClient.NEWLINE;
@@ -20,7 +21,7 @@ public class Email {
 		PLAIN, HTML
 	}
 	private static final SimpleDateFormat dateFormatter = 
-		new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z");
+		new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z", Locale.ENGLISH);
     private static final Pattern PATTERN_NEWLINE = Pattern.compile("(\\r\\n|\\n)");
 
 	private String fromAddress;
diff --git a/test/zutil/net/smtp/EmailTest.java b/test/zutil/net/smtp/EmailTest.java
index 887772b..9400fdd 100644
--- a/test/zutil/net/smtp/EmailTest.java
+++ b/test/zutil/net/smtp/EmailTest.java
@@ -86,7 +86,7 @@ public class EmailTest {
         assertEquals(
                 "From: test@example.com" + NEWLINE +
                         "To: to@example.com" + NEWLINE +
-                        "Date: on, 22 nov 2000 15:20:55 +0100" + NEWLINE +
+                        "Date: Wed, 22 Nov 2000 15:20:55 +0100" + NEWLINE +
                         "Content-Type: text/plain;" + NEWLINE +
                         "Subject: " + NEWLINE +
                         NEWLINE +
@@ -109,7 +109,7 @@ public class EmailTest {
                 "From: Test Tester <test@example.com>" + NEWLINE +
                         "Reply-To: <mokey@example.org>" + NEWLINE +
                         "To: To Totter <to@example.com>" + NEWLINE +
-                        "Date: on, 22 nov 2000 15:20:55 +0100" + NEWLINE +
+                        "Date: Wed, 22 Nov 2000 15:20:55 +0100" + NEWLINE +
                         "Content-Type: text/html;" + NEWLINE +
                         "Subject: Title" + NEWLINE +
                         NEWLINE +