diff --git a/lib/fund.js b/lib/fund.js
index 217a21d1fc3e3..25d3462f63869 100644
--- a/lib/fund.js
+++ b/lib/fund.js
@@ -63,7 +63,7 @@ class Fund extends BaseCommand {
     const fundingSourceNumber = numberArg && parseInt(numberArg, 10)
 
     const badFundingSourceNumber =
-      numberArg !== undefined &&
+      numberArg !== null &&
       (String(fundingSourceNumber) !== numberArg || fundingSourceNumber < 1)
 
     if (badFundingSourceNumber) {
diff --git a/test/lib/fund.js b/test/lib/fund.js
index bd600dbf75c01..8c10007844f0a 100644
--- a/test/lib/fund.js
+++ b/test/lib/fund.js
@@ -186,7 +186,7 @@ const config = {
   json: false,
   global: false,
   unicode: false,
-  which: undefined,
+  which: null,
 }
 const openUrl = async (npm, url, msg) => {
   if (url === 'http://npmjs.org')
@@ -563,7 +563,7 @@ test('fund using nested packages with multiple sources, with a source number', t
     t.ifError(err, 'should not error out')
     t.matchSnapshot(printUrl, 'should open the numbered URL')
 
-    config.which = undefined
+    config.which = null
     printUrl = ''
     t.end()
   })
@@ -663,7 +663,7 @@ test('fund using bad which value', t => {
       'should have bad which option error message'
     )
 
-    config.which = undefined
+    config.which = null
     result = ''
     t.end()
   })