diff --git a/2006/birken/README.md b/2006/birken/README.md
index b246c5fc9..a1a2d85ef 100644
--- a/2006/birken/README.md
+++ b/2006/birken/README.md
@@ -18,6 +18,10 @@ make
 ./birken < file.tofu
 ```
 
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed a segfault in
+macOS with this entry. The problem was a missing `+1` for strlen() with
+malloc(). Thank you Cody for your assistance!
+
 ### Try:
 
 ```sh
diff --git a/2006/birken/birken.c b/2006/birken/birken.c
index eb5398792..638705d15 100644
--- a/2006/birken/birken.c
+++ b/2006/birken/birken.c
@@ -64,7 +64,7 @@ _=z->o; c=_->o->_; a= c->_->_->o; c=_
 ->c++; h(c); } Q Z(a->c<c->c){ a
 ->c++; h(a); } z=z->_; } } X*
 v(X*_,int O){ X*s=(X*)m\
-alloc(strlen(_)*siz\
+alloc(1+strlen(_)*siz\
 eof(X)); X*l=s;
 J((*l++=*_?
 *_-O:0)