diff --git a/lib/completion.ts b/lib/completion.ts
index c93405bcc..d8d84f01c 100644
--- a/lib/completion.ts
+++ b/lib/completion.ts
@@ -128,7 +128,7 @@ export class Completion implements CompletionInstance {
         if (
           !isPositionalKey &&
           !options.hiddenOptions.includes(key) &&
-          !this.argsContainKey(args, argv, key, negable)
+          !this.argsContainKey(args, key, negable)
         ) {
           this.completeOptionKey(key, completions, current);
           if (negable && !!options.default[key])
@@ -229,17 +229,16 @@ export class Completion implements CompletionInstance {
 
   private argsContainKey(
     args: string[],
-    argv: Arguments,
     key: string,
     negable: boolean
   ): boolean {
-    if (args.indexOf(`--${key}`) !== -1) return true;
-    if (negable && args.indexOf(`--no-${key}`) !== -1) return true;
+    const argsContains = (s: string) =>
+      args.indexOf((/^[^0-9]$/.test(s) ? '-' : '--') + s) !== -1;
+    if (argsContains(key)) return true;
+    if (negable && argsContains(`no-${key}`)) return true;
     if (this.aliases) {
-      // search for aliases in parsed argv
-      // can't do the same thing for main option names because argv can contain default values
       for (const alias of this.aliases[key]) {
-        if (argv[alias] !== undefined) return true;
+        if (argsContains(alias)) return true;
       }
     }
     return false;
diff --git a/test/completion.cjs b/test/completion.cjs
index 9c5e032a2..ff7027121 100644
--- a/test/completion.cjs
+++ b/test/completion.cjs
@@ -163,6 +163,50 @@ describe('Completion', () => {
           r.logs.should.include('--bar');
         });
 
+        it('includes flags that have default', () => {
+          const r = checkUsage(
+            () =>
+              yargs([
+                './completion',
+                '--get-yargs-completions',
+                '--used',
+                '--no-usedwithnegation',
+                '-x',
+                '',
+              ])
+                .help(false)
+                .version(false)
+                .options({
+                  used: {type: 'boolean', default: true},
+                  usedwithnegation: {type: 'boolean', default: true},
+                  usedwithalias: {
+                    type: 'boolean',
+                    alias: ['x', 'y'],
+                    default: true,
+                  },
+                  somebool: {type: 'boolean', default: false},
+                  somebool2: {type: 'boolean', default: true},
+                  somestringwithalias: {
+                    type: 'string',
+                    alias: 's',
+                    default: 'foo',
+                  },
+                })
+                .help(false)
+                .parserConfiguration({'boolean-negation': true}).argv
+          );
+
+          r.logs
+            .sort()
+            .should.deep.eq([
+              '--no-somebool2',
+              '--somebool',
+              '--somebool2',
+              '--somestringwithalias',
+              '-s',
+            ]);
+        });
+
         it('completes options for the correct command', () => {
           process.env.SHELL = '/bin/bash';
           const r = checkUsage(