diff --git a/rimraf.js b/rimraf.js
index e80dd10..18f2e68 100644
--- a/rimraf.js
+++ b/rimraf.js
@@ -4,7 +4,12 @@ rimraf.sync = rimrafSync
 var assert = require("assert")
 var path = require("path")
 var fs = require("fs")
-var glob = require("glob")
+let glob = undefined
+try {
+  glob = require("glob")
+} catch (_err) {
+  // treat glob as optional.
+}
 var _0666 = parseInt('666', 8)
 
 var defaultGlobOpts = {
@@ -37,6 +42,9 @@ function defaults (options) {
   if (options.glob === false) {
     options.disableGlob = true
   }
+  if (options.disableGlob !== true && glob === undefined) {
+    throw Error('glob dependency not found, set `options.disableGlob = true` if intentional')
+  }
   options.disableGlob = options.disableGlob || false
   options.glob = options.glob || defaultGlobOpts
 }