diff --git a/src/org/jruby/ext/Readline.java b/src/org/jruby/ext/Readline.java
index 340a132668f..7f67805a619 100644
--- a/src/org/jruby/ext/Readline.java
+++ b/src/org/jruby/ext/Readline.java
@@ -54,6 +54,7 @@
 import jline.FileNameCompletor;
 import jline.CandidateListCompletionHandler;
 import jline.History;
+import org.jruby.CompatVersion;
 import org.jruby.RubyIO;
 import org.jruby.RubyNumeric;
 import org.jruby.RubyString;
@@ -244,6 +245,18 @@ public static IRubyObject s_readline(ThreadContext context, IRubyObject recv, IR
         return line;
     }
 
+    @JRubyMethod(name = "input=", module = true, visibility = Visibility.PRIVATE, compat = CompatVersion.RUBY1_9)
+    public static IRubyObject setInput(ThreadContext context, IRubyObject recv, IRubyObject input) {
+        // FIXME: JRUBY-3604
+        return context.getRuntime().getNil();
+    }
+
+    @JRubyMethod(name = "output=", module = true, visibility = Visibility.PRIVATE, compat = CompatVersion.RUBY1_9)
+    public static IRubyObject setOutput(ThreadContext context, IRubyObject recv, IRubyObject output) {
+        // FIXME: JRUBY-3604
+        return context.getRuntime().getNil();
+    }
+
     @JRubyMethod(name = "readline", module = true, visibility = Visibility.PRIVATE)
     public static IRubyObject s_readline(IRubyObject recv, IRubyObject prompt) throws IOException {
         return s_readline(recv, prompt, recv.getRuntime().getFalse());