diff --git a/.travis.yml b/.travis.yml
index e1fcfa9b..5978c61d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,8 +3,8 @@ language: rust
 cache: pip
 
 install:
-  - bash ci/install.sh
   - source ~/.cargo/env || true
+  - bash ci/install.sh
 
 script:
   - true
diff --git a/ci/install.sh b/ci/install.sh
index d9cb369e..dd96daf1 100644
--- a/ci/install.sh
+++ b/ci/install.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
 set -ex
 
+cargo install cargo install mdbook --vers "0.0.28"
+
 if command -v ghp-import >/dev/null 2>&1; then
     pip install ghp-import
-fi
\ No newline at end of file
+fi