diff --git a/browser/base/content/aboutDialog.css b/browser/base/content/aboutDialog.css
index 91397283d132..8911dd838b2b 100644
--- a/browser/base/content/aboutDialog.css
+++ b/browser/base/content/aboutDialog.css
@@ -4,6 +4,10 @@
 
 #aboutDialog {
   width: 620px;
+  /* Set an explicit line-height to avoid discrepancies in 'auto' spacing
+     across screens with different device DPI, which may cause font metrics
+     to round differently. */
+  line-height: 1.5;
 }
 
 #rightBox {