diff --git a/AppKit/CPTextView/CPTypesetter.j b/AppKit/CPTextView/CPTypesetter.j
index 95cb70153..85c3f1991 100644
--- a/AppKit/CPTextView/CPTypesetter.j
+++ b/AppKit/CPTextView/CPTypesetter.j
@@ -49,7 +49,23 @@ CPTypesetterParagraphBreakAction  = 1 << 4;
 CPTypesetterContainerBreakAction  = 1 << 5;
 
 var CPSystemTypesetterFactory,
-    _sharedSimpleTypesetter;
+    _sharedSimpleTypesetter,
+    _CPTypesetterCachedDecimalSeparator = nil;
+
+/*
+    Returns the decimal separator of the user's locale, which a decimal tab stop aligns on.
+*/
+var _CPTypesetterDecimalSeparator = function()
+{
+    if (!_CPTypesetterCachedDecimalSeparator)
+    {
+        var formatted = (1.5).toLocaleString();
+
+        _CPTypesetterCachedDecimalSeparator = formatted.length === 3 ? formatted.charAt(1) : @".";
+    }
+
+    return _CPTypesetterCachedDecimalSeparator;
+};
 
 @implementation CPTypesetter : CPObject
 
@@ -478,7 +494,16 @@ var CPSystemTypesetterFactory,
                         tabAlignment = [nextTab alignment];
 
                     // Mathematically offset the tab character's right boundary
-                    if (tabAlignment === CPCenterTextAlignment)
+                    if ([nextTab tabStopType] === CPDecimalTabStopType)
+                    {
+                        // As in Cocoa, the first decimal separator of the user's locale starts at the stop.
+                        // A segment without one ends at the stop, like a right tab.
+                        var separatorIndex = segmentString.indexOf(_CPTypesetterDecimalSeparator()),
+                            widthBeforeSeparator = separatorIndex === -1 ? nextSegmentWidth : [segmentString.substring(0, separatorIndex) sizeWithFont:currentFont inWidth:NULL].width;
+
+                        rangeWidth = (tabLocation - widthBeforeSeparator) - lineOrigin.x;
+                    }
+                    else if (tabAlignment === CPCenterTextAlignment)
                     {
                         rangeWidth = (tabLocation - nextSegmentWidth / 2.0) - lineOrigin.x;
                     }
diff --git a/Tests/Manual/TextEditor/WORKLIST.md b/Tests/Manual/TextEditor/WORKLIST.md
index 94084ac73..003f57b33 100644
--- a/Tests/Manual/TextEditor/WORKLIST.md
+++ b/Tests/Manual/TextEditor/WORKLIST.md
@@ -61,6 +61,7 @@ TextEditor is a document-based test application and a tutorial. When the app use
 - The Window menu lists the open document windows, marks the main window with a check mark and brings a window to the front when chosen. Bring All to Front can be tested once documents open in separate browser windows.
 - The About panel shows the display name from `CPBundleDisplayName`.
 - Edit > Allow Undo turns undo on and off for the active document. With undo off, Undo and Redo stay disabled, and the check mark follows the document in front.
-- The ruler: markers follow the paragraph at the selection; first line, head and right indents change the layout as shown; clicking adds a tab stop, and dragging moves or removes one; the Control-click menu on a tab stop appears (its effect is not yet verified, for lack of tabbed text); the ruler's zero lines up with the start of the text, and markers at 0 are fully visible.
+- The ruler: markers follow the paragraph at the selection; first line, head and right indents change the layout as shown; clicking adds a tab stop, and dragging moves or removes one; the Control-click menu changes a tab stop's type; the ruler's zero lines up with the start of the text, and markers at 0 are fully visible.
 - Text stays inside the visible width, with Cocoa's 5-point line fragment padding.
+- Tab characters: the Tab key inserts a tab in the text view, and left, centre, right and decimal tab stops align their columns.
 - Builds with both the legacy toolchain and capp-build.