diff --git a/lib/excon/test/plugin/server/exec.rb b/lib/excon/test/plugin/server/exec.rb
index 7f86d157..f790d959 100644
--- a/lib/excon/test/plugin/server/exec.rb
+++ b/lib/excon/test/plugin/server/exec.rb
@@ -4,10 +4,13 @@ module Plugin
       module Server
         module Exec
           def start(app_str = app)
-            line = ''
             open_process(app_str)
+            process_stderr = ""
+            line = ''
             until line =~ /\Aready\Z/
               line = error.gets
+              raise process_stderr if line.nil?
+              process_stderr << line
               fatal_time = elapsed_time > timeout
               if fatal_time
                 msg = "executable #{app_str} has taken too long to start"
diff --git a/lib/excon/test/plugin/server/puma.rb b/lib/excon/test/plugin/server/puma.rb
index d87a8af6..69e11206 100644
--- a/lib/excon/test/plugin/server/puma.rb
+++ b/lib/excon/test/plugin/server/puma.rb
@@ -5,9 +5,12 @@ module Server
         module Puma
           def start(app_str = app, bind_uri = bind)
             open_process('puma', '-b', bind_uri.to_s, app_str)
+            process_stderr = ""
             line = ''
             until line =~ /Use Ctrl-C to stop/
               line = read.gets
+              raise process_stderr if line.nil?
+              process_stderr << line
               fatal_time = elapsed_time > timeout
               raise 'puma server has taken too long to start' if fatal_time
             end
diff --git a/lib/excon/test/plugin/server/unicorn.rb b/lib/excon/test/plugin/server/unicorn.rb
index 990502d0..73a45e99 100644
--- a/lib/excon/test/plugin/server/unicorn.rb
+++ b/lib/excon/test/plugin/server/unicorn.rb
@@ -20,9 +20,12 @@ def start(app_str = app, bind_uri = bind)
               app_str
             ]
             open_process(*args)
+            process_stderr = ''
             line = ''
             until line =~ /worker\=0 ready/
               line = error.gets
+              raise process_stderr if line.nil?
+              process_stderr << line
               fatal_time = elapsed_time > timeout
               raise 'unicorn server has taken too long to start' if fatal_time
             end
diff --git a/lib/excon/test/plugin/server/webrick.rb b/lib/excon/test/plugin/server/webrick.rb
index 19354d52..afe6c540 100644
--- a/lib/excon/test/plugin/server/webrick.rb
+++ b/lib/excon/test/plugin/server/webrick.rb
@@ -8,9 +8,12 @@ def start(app_str = app, bind_uri = bind)
             host = bind_uri.host.gsub(/[\[\]]/, '')
             port = bind_uri.port.to_s
             open_process('rackup', '-s', 'webrick', '--host', host, '--port', port, app_str)
+            process_stderr = ""
             line = ''
             until line =~ /HTTPServer#start/
               line = error.gets
+              raise process_stderr if line.nil?
+              process_stderr << line
               fatal_time = elapsed_time > timeout
               raise 'webrick server has taken too long to start' if fatal_time
             end
diff --git a/tests/test_helper.rb b/tests/test_helper.rb
index 08bc4951..62dc6b2d 100644
--- a/tests/test_helper.rb
+++ b/tests/test_helper.rb
@@ -246,7 +246,11 @@ def rackup_path(*parts)
 
 def with_rackup(name, host="127.0.0.1")
   pid, w, r, e = launch_process("rackup", "-s", "webrick", "--host", host, rackup_path(name))
-  until e.gets =~ /HTTPServer#start:/; end
+  process_stderr = ""
+  until (line = e.gets) =~ /HTTPServer#start:/
+    raise process_stderr if line.nil?
+    process_stderr << line
+  end
   yield
 ensure
   cleanup_process(pid)
@@ -271,7 +275,11 @@ def with_unicorn(name, listen='127.0.0.1:9292')
   unless RUBY_PLATFORM == 'java'
     unix_socket = listen.sub('unix://', '') if listen.start_with? 'unix://'
     pid, w, r, e = launch_process("unicorn", "--no-default-middleware","-l", listen, rackup_path(name))
-    until e.gets =~ /worker=0 ready/; end
+    process_stderr = ""
+    until (line = e.gets) =~ /worker=0 ready/
+      raise process_stderr if line.nil?
+      process_stderr << line
+    end
   else
     # need to find suitable server for jruby
   end
@@ -290,7 +298,11 @@ def server_path(*parts)
 
 def with_server(name)
   pid, w, r, e = launch_process("ruby", server_path("#{name}.rb"))
-  until e.gets =~ /ready/; end
+  process_stderr = ""
+  until (line = e.gets) =~ /ready/
+    raise process_stderr if line.nil?
+    process_stderr << line
+  end
   yield
 ensure
   cleanup_process(pid)