gistfile.patch

diff --git a/lib/arborist/reify.js b/lib/arborist/reify.js
index 9854d2d..54325aa 100644
--- a/lib/arborist/reify.js
+++ b/lib/arborist/reify.js
@@ -233,12 +233,18 @@ module.exports = cls => class Reifier extends cls {
         .then(() => process.emit('timeEnd', 'reify:loadTrees'))
     }
 
+    const updateNames = options.update && options.update.names || []
     const actualOpt = this[_global] ? {
       ignoreMissing: true,
       global: true,
-      filter: (node, kid) => this[_explicitRequests].size === 0 || !node.isProjectRoot
-        ? true
-        : (node.edgesOut.has(kid) || this[_explicitRequests].has(kid)),
+      filter: (node, kid) => {
+        const explicits = new Set([
+          ...this[_explicitRequests],
+          ...updateNames,
+        ])
+        return explicits.size === 0 || !node.isProjectRoot ? true
+          : (node.edgesOut.has(kid) || explicits.has(kid))
+      }
     } : { ignoreMissing: true }
 
     if (!this[_global]) {

test file:

#!/usr/bin/env bash

not_expect () {
  if [ -d $1 ]; then
    echo "SHOULD BE MISSING: $1"
    exit 1
  fi
}

expect () {
  if ! [ -d $1 ]; then
    echo "MISSING: $1"
    exit 1
  fi
}

rm -rf global-prefix
arborist reify global-prefix --global --add=abbrev@1.0
ls -laF global-prefix/node_modules
expect global-prefix/node_modules/abbrev
not_expect global-prefix/node_modules/once

arborist reify global-prefix --global --add=once
ls -laF global-prefix/node_modules
expect global-prefix/node_modules/abbrev
expect global-prefix/node_modules/once

arborist reify global-prefix --global --update=abbrev
ls -laF global-prefix/node_modules
expect global-prefix/node_modules/abbrev
expect global-prefix/node_modules/once