diff --git a/doc/metropolistheme.pdf b/doc/metropolistheme.pdf
index fb3294c..d529433 100644
Binary files a/doc/metropolistheme.pdf and b/doc/metropolistheme.pdf differ
diff --git a/source/beamerouterthememetropolis.dtx b/source/beamerouterthememetropolis.dtx
index aee9493..8a7accf 100644
--- a/source/beamerouterthememetropolis.dtx
+++ b/source/beamerouterthememetropolis.dtx
@@ -87,23 +87,23 @@
   /metropolis/outer/frametitleformat/.cd,
     .is choice,
     regular/.code={%
-       \renewcommand{\@metropolis@frametitleformat}{}%
-       \renewcommand{\@metropolis@frametitlestrut}{%
-           \rule{0pt}{\heightof{ABCDEFGHIJKLMNOPQRSTUVWXYZ}}
-       }
-       },
+      \renewcommand{\@metropolis@frametitleformat}{}%
+      \renewcommand{\@metropolis@frametitlestrut}{%
+        \vphantom{ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz}%
+      }
+    },
     lowercase/.code={%
-       \renewcommand{\@metropolis@frametitleformat}{\MakeLowercase}%
-       \renewcommand{\@metropolis@frametitlestrut}{%
-           \rule{0pt}{\heightof{abcdefghijklmnopqrstuvwxyz}}
-       }
-       },
+      \renewcommand{\@metropolis@frametitleformat}{\MakeLowercase}%
+      \renewcommand{\@metropolis@frametitlestrut}{%
+        \vphantom{abcdefghijklmnopqrstuvwxyz}%
+      }
+    },
     uppercase/.code={%
-       \renewcommand{\@metropolis@frametitleformat}{\MakeUppercase}%
-       \renewcommand{\@metropolis@frametitlestrut}{%
-           \rule{0pt}{\heightof{ABCDEFGHIJKLMNOPQRSTUVWXYZ}}
-       }
-       },
+      \renewcommand{\@metropolis@frametitleformat}{\MakeUppercase}%
+      \renewcommand{\@metropolis@frametitlestrut}{%
+        \vphantom{ABCDEFGHIJKLMNOPQRSTUVWXYZ}%
+      }
+    },
 }
 %    \end{macrocode}
 % \end{macro}