travis: Typing Darwin is really hard.
diff --git a/.travis/install.sh b/.travis/install.sh
index 340571e..3582ea1 100755
--- a/.travis/install.sh
+++ b/.travis/install.sh
@@ -3,7 +3,7 @@
 set -e
 set -x
 
-if [[ "$(uname -s)" == 'Dawin' ]]; then
+if [[ "$(uname -s)" == 'Darwin' ]]; then
     DARWIN=true
 else
     DARWIN=false