SF bug 799367: grammar error
diff --git a/Doc/lib/libdatetime.tex b/Doc/lib/libdatetime.tex
index e97d11f..96b1274 100644
--- a/Doc/lib/libdatetime.tex
+++ b/Doc/lib/libdatetime.tex
@@ -819,7 +819,7 @@
\code{\var{dt}.replace(tzinfo=None)}.
Note that the default \method{tzinfo.fromutc()} method can be overridden
- in a \class{tzinfo} subclass to effect the result returned by
+ in a \class{tzinfo} subclass to affect the result returned by
\method{astimezone()}. Ignoring error cases, \method{astimezone()}
acts like: