diff --git a/tests/e2e/select-input-source.swift b/tests/e2e/select-input-source.swift
index fe8ecf52258..3012e76e8d3 100644
--- a/tests/e2e/select-input-source.swift
+++ b/tests/e2e/select-input-source.swift
@@ -6,9 +6,27 @@ guard CommandLine.arguments.count == 2 else {
 
 let properties = [kTISPropertyInputSourceID: CommandLine.arguments[1] as CFString] as CFDictionary
 let sources = TISCreateInputSourceList(properties, true).takeRetainedValue() as! [TISInputSource]
-guard let source = sources.first else {
+guard !sources.isEmpty else {
   exit(3)
 }
 
-TISEnableInputSource(source)
+func boolProperty(_ source: TISInputSource, _ key: CFString) -> Bool {
+  guard let raw = TISGetInputSourceProperty(source, key) else { return false }
+  return unsafeBitCast(raw, to: CFBoolean.self) == kCFBooleanTrue
+}
+
+// Why: one id can expose several entries — a third-party IME publishes a non-selectable
+// parent alongside the selectable mode, and `sources.first` can return the parent, which
+// then fails TISSelectInputSource with paramErr (-50). Qingg is the case that found this.
+let selectable = sources.filter { boolProperty($0, kTISPropertyInputSourceIsSelectCapable) }
+guard let source = selectable.first ?? sources.first else {
+  exit(3)
+}
+
+// Enable every entry for the id, not just the selected one: selecting a mode whose parent
+// is still disabled also fails with -50.
+for candidate in sources {
+  TISEnableInputSource(candidate)
+}
+
 exit(TISSelectInputSource(source) == noErr ? 0 : 4)