diff --git a/src/org/jruby/RubyKernel.java b/src/org/jruby/RubyKernel.java
index 7c83c5595de..94770078827 100644
--- a/src/org/jruby/RubyKernel.java
+++ b/src/org/jruby/RubyKernel.java
@@ -1667,7 +1667,7 @@ private static RubyNumeric randCommon(ThreadContext context, Ruby runtime, Rando
     @JRubyMethod(name = "spawn", required = 1, rest = true, module = true, visibility = PRIVATE, compat = RUBY1_9)
     public static RubyFixnum spawn(ThreadContext context, IRubyObject recv, IRubyObject[] args) {
         Ruby runtime = context.getRuntime();
-        long pid = ShellLauncher.runWithoutWait(runtime, args);
+        long pid = ShellLauncher.runExternalWithoutWait(runtime, args);
         return RubyFixnum.newFixnum(runtime, pid);
     }
 
diff --git a/src/org/jruby/RubyProcess.java b/src/org/jruby/RubyProcess.java
index 0057fd32924..39ce3f40c37 100644
--- a/src/org/jruby/RubyProcess.java
+++ b/src/org/jruby/RubyProcess.java
@@ -950,7 +950,7 @@ public static IRubyObject fork(ThreadContext context, IRubyObject recv, Block bl
     @JRubyMethod(name = "spawn", required = 1, rest = true, module = true, compat = CompatVersion.RUBY1_9)
     public static RubyFixnum spawn(ThreadContext context, IRubyObject recv, IRubyObject[] args) {
         Ruby runtime = context.getRuntime();
-        long pid = ShellLauncher.runWithoutWait(runtime, args);
+        long pid = ShellLauncher.runExternalWithoutWait(runtime, args);
         return RubyFixnum.newFixnum(runtime, pid);
     }
     
diff --git a/src/org/jruby/util/ShellLauncher.java b/src/org/jruby/util/ShellLauncher.java
index 353c7ea76a2..82993ac9e51 100644
--- a/src/org/jruby/util/ShellLauncher.java
+++ b/src/org/jruby/util/ShellLauncher.java
@@ -371,6 +371,10 @@ public static long runWithoutWait(Ruby runtime, IRubyObject[] rawArgs) {
         return runWithoutWait(runtime, rawArgs, runtime.getOutputStream());
     }
 
+    public static long runExternalWithoutWait(Ruby runtime, IRubyObject[] rawArgs) {
+        return runWithoutWait(runtime, rawArgs, runtime.getOutputStream());
+    }
+
     public static int execAndWait(Ruby runtime, IRubyObject[] rawArgs) {
         File pwd = new File(runtime.getCurrentDirectory());
         LaunchConfig cfg = new LaunchConfig(runtime, rawArgs, true);
@@ -414,7 +418,7 @@ public static int runAndWait(Ruby runtime, IRubyObject[] rawArgs, OutputStream o
         }
     }
 
-    public static long runWithoutWait(Ruby runtime, IRubyObject[] rawArgs, OutputStream output) {
+    private static long runWithoutWait(Ruby runtime, IRubyObject[] rawArgs, OutputStream output) {
         OutputStream error = runtime.getErrorStream();
         try {
             Process aProcess = run(runtime, rawArgs, true);
@@ -425,6 +429,17 @@ public static long runWithoutWait(Ruby runtime, IRubyObject[] rawArgs, OutputStr
         }
     }
 
+    private static long runExternalWithoutWait(Ruby runtime, IRubyObject[] rawArgs, OutputStream output) {
+        OutputStream error = runtime.getErrorStream();
+        try {
+            Process aProcess = run(runtime, rawArgs, true, true);
+            handleStreamsNonblocking(runtime, aProcess, output, error);
+            return getPidFromProcess(aProcess);
+        } catch (IOException e) {
+            throw runtime.newIOErrorFromException(e);
+        }
+    }
+
     public static long getPidFromProcess(Process process) {
         if (process instanceof ScriptThreadProcess) {
             return process.hashCode();
@@ -1119,12 +1134,16 @@ private static boolean shouldVerifyPathExecutable(String cmdline) {
     }
 
     public static Process run(Ruby runtime, IRubyObject[] rawArgs, boolean doExecutableSearch) throws IOException {
+        return run(runtime, rawArgs, doExecutableSearch, false);
+    }
+
+    public static Process run(Ruby runtime, IRubyObject[] rawArgs, boolean doExecutableSearch, boolean forceExternalProcess) throws IOException {
         Process aProcess = null;
         File pwd = new File(runtime.getCurrentDirectory());
         LaunchConfig cfg = new LaunchConfig(runtime, rawArgs, doExecutableSearch);
 
         try {
-            if (cfg.shouldRunInProcess()) {
+            if (!forceExternalProcess && cfg.shouldRunInProcess()) {
                 log(runtime, "Launching in-process");
                 ScriptThreadProcess ipScript = new ScriptThreadProcess(
                         runtime, cfg.getExecArgs(), getCurrentEnv(runtime), pwd);