diff --git a/flags/bool_test.ts b/flags/bool_test.ts
index a33e9be0b1c3..422ae0933503 100755
--- a/flags/bool_test.ts
+++ b/flags/bool_test.ts
@@ -155,3 +155,14 @@ test(function booleanParsingFalse(): void {
 
   assertEquals(parsed.boool, false);
 });
+
+test(function booleanParsingTrueLike(): void {
+  const parsed = parse(["-t", "true123"], { boolean: ["t"] });
+  assertEquals(parsed.t, true);
+
+  const parsed2 = parse(["-t", "123"], { boolean: ["t"] });
+  assertEquals(parsed2.t, true);
+
+  const parsed3 = parse(["-t", "false123"], { boolean: ["t"] });
+  assertEquals(parsed3.t, true);
+});
diff --git a/flags/mod.ts b/flags/mod.ts
index 0ebaaf52eb15..61cd06f911ad 100644
--- a/flags/mod.ts
+++ b/flags/mod.ts
@@ -271,7 +271,7 @@ export function parse(
         ) {
           setArg(key, args[i + 1], arg);
           i++;
-        } else if (args[i + 1] && /true|false/.test(args[i + 1])) {
+        } else if (args[i + 1] && /^(true|false)$/.test(args[i + 1])) {
           setArg(key, args[i + 1] === "true", arg);
           i++;
         } else {