diff --git a/tufte-common.def b/tufte-common.def
index faa20a2..32935e4 100644
--- a/tufte-common.def
+++ b/tufte-common.def
@@ -1,5 +1,5 @@
 %%
-%% This file contains the code that's common to the Tufte-LaTeX document classes.
+%% This file contains the code that is common to the Tufte-LaTeX document classes.
 %%
 
 \ProvidesFile{tufte-common.def}[2009/12/11 v3.5.0 Common code for the Tufte-LaTeX styles]