diff --git a/circle.yml b/circle.yml
index 84d386e4..5f7a6210 100644
--- a/circle.yml
+++ b/circle.yml
@@ -1,6 +1,6 @@
 machine:
   node:
-    version: v4.6.1
+    version: v4.8.4
   services:
     - docker
 test:
diff --git a/docs/install.md b/docs/install.md
index 5f08ce60..d2cce612 100644
--- a/docs/install.md
+++ b/docs/install.md
@@ -55,7 +55,7 @@ libvips is available in the
 [testing repository](https://pkgs.alpinelinux.org/packages?name=vips-dev):
 
 ```sh
-apk add vips-dev --update-cache --repository https://dl-3.alpinelinux.org/alpine/edge/testing/
+apk add vips-dev fftw-dev --update-cache --repository https://dl-3.alpinelinux.org/alpine/edge/testing/
 ```
 
 The smaller stack size of musl libc means