diff --git a/layout/base/nsPresContext.cpp b/layout/base/nsPresContext.cpp
index 0f03edcbe0c..b12d2b256d7 100644
--- a/layout/base/nsPresContext.cpp
+++ b/layout/base/nsPresContext.cpp
@@ -729,7 +729,7 @@ nsPresContext::Init(nsIDeviceContext* aDeviceContext)
   mInitialized = PR_TRUE;
 #endif
 
-  float pixelsToTwips = PixelsToTwips();
+  float pixelsToTwips = ScaledPixelsToTwips();
   mBorderWidthTable[NS_STYLE_BORDER_WIDTH_THIN] = NSIntPixelsToTwips(1, pixelsToTwips);
   mBorderWidthTable[NS_STYLE_BORDER_WIDTH_MEDIUM] = NSIntPixelsToTwips(3, pixelsToTwips);
   mBorderWidthTable[NS_STYLE_BORDER_WIDTH_THICK] = NSIntPixelsToTwips(5, pixelsToTwips);
diff --git a/layout/base/nsPresContext.h b/layout/base/nsPresContext.h
index ef91b34f23c..53e770a0706 100644
--- a/layout/base/nsPresContext.h
+++ b/layout/base/nsPresContext.h
@@ -388,6 +388,11 @@ public:
    */
   NS_HIDDEN_(void) SetPageDim(const nsRect& aRect);
 
+  /**
+   * Conversion from device pixels to twips.
+   * WARNING: The misuse of this function to convert CSS pixels to twips 
+   * will cause problems during printing
+   */
   float PixelsToTwips() const { return mDeviceContext->DevUnitsToAppUnits(); }
 
   float TwipsToPixels() const { return mDeviceContext->AppUnitsToDevUnits(); }
@@ -396,7 +401,7 @@ public:
 
   //XXX this is probably not an ideal name. MMP
   /** 
-   * Do pixels to twips conversion taking into account
+   * Do CSS pixels to twips conversion taking into account
    * differing size of a "pixel" from device to device.
    */
   NS_HIDDEN_(float) ScaledPixelsToTwips() const;