diff --git a/support/testing/infra/__init__.py b/support/testing/infra/__init__.py
index b5634f6f64..a55ad7fdf5 100644
--- a/support/testing/infra/__init__.py
+++ b/support/testing/infra/__init__.py
@@ -8,24 +8,17 @@ from urllib2 import urlopen, HTTPError, URLError
 
 ARTIFACTS_URL = "http://autobuild.buildroot.net/artefacts/"
 
-@contextlib.contextmanager
-def smart_open(filename=None):
+def open_log_file(builddir, stage, logtofile=True):
     """
-    Return a file-like object that can be written to using the 'with'
-    keyword, as in the example:
-    with infra.smart_open("test.log") as outfile:
-       outfile.write("Hello, world!\n")
+    Open a file for logging and return its handler.
+    If logtofile is True, returns sys.stdout. Otherwise opens a file
+    with a suitable name in the build directory.
     """
-    if filename and filename != '-':
-        fhandle = open(filename, 'a+')
+    if logtofile:
+        fhandle = open("{}-{}.log".format(builddir, stage), 'a+')
     else:
         fhandle = sys.stdout
-
-    try:
-        yield fhandle
-    finally:
-        if fhandle is not sys.stdout:
-            fhandle.close()
+    return fhandle
 
 def filepath(relpath):
     return os.path.join(os.getcwd(), "support/testing", relpath)
diff --git a/support/testing/infra/builder.py b/support/testing/infra/builder.py
index 105da01ca2..a475bb0a30 100644
--- a/support/testing/infra/builder.py
+++ b/support/testing/infra/builder.py
@@ -8,16 +8,12 @@ class Builder(object):
     def __init__(self, config, builddir, logtofile):
         self.config = config
         self.builddir = builddir
-        self.logtofile = logtofile
+        self.logfile = infra.open_log_file(builddir, "build", logtofile)
 
     def build(self):
         if not os.path.isdir(self.builddir):
             os.makedirs(self.builddir)
 
-        log = "{}-build.log".format(self.builddir)
-        if not self.logtofile:
-            log = None
-
         config_file = os.path.join(self.builddir, ".config")
         with open(config_file, "w+") as cf:
             cf.write(self.config)
@@ -25,14 +21,12 @@ class Builder(object):
         cmd = ["make",
                "O={}".format(self.builddir),
                "olddefconfig"]
-        with infra.smart_open(log) as log_fh:
-            ret = subprocess.call(cmd, stdout=log_fh, stderr=log_fh)
+        ret = subprocess.call(cmd, stdout=self.logfile, stderr=self.logfile)
         if ret != 0:
             raise SystemError("Cannot olddefconfig")
 
         cmd = ["make", "-C", self.builddir]
-        with infra.smart_open(log) as log_fh:
-            ret = subprocess.call(cmd, stdout=log_fh, stderr=log_fh)
+        ret = subprocess.call(cmd, stdout=self.logfile, stderr=self.logfile)
         if ret != 0:
             raise SystemError("Build failed")
 
diff --git a/support/testing/infra/emulator.py b/support/testing/infra/emulator.py
index 7c476cb0e4..2480b46540 100644
--- a/support/testing/infra/emulator.py
+++ b/support/testing/infra/emulator.py
@@ -14,9 +14,7 @@ class Emulator(object):
         self.__tn = None
         self.downloaddir = downloaddir
         self.log = ""
-        self.log_file = "{}-run.log".format(builddir)
-        if logtofile is None:
-            self.log_file = None
+        self.logfile = infra.open_log_file(builddir, "run", logtofile)
 
     # Start Qemu to boot the system
     #
@@ -72,9 +70,8 @@ class Emulator(object):
         if kernel_cmdline:
             qemu_cmd += ["-append", " ".join(kernel_cmdline)]
 
-        with infra.smart_open(self.log_file) as lfh:
-            lfh.write("> starting qemu with '%s'\n" % " ".join(qemu_cmd))
-            self.qemu = subprocess.Popen(qemu_cmd, stdout=lfh, stderr=lfh)
+        self.logfile.write("> starting qemu with '%s'\n" % " ".join(qemu_cmd))
+        self.qemu = subprocess.Popen(qemu_cmd, stdout=self.logfile, stderr=self.logfile)
 
         # Wait for the telnet port to appear and connect to it.
         while True:
@@ -88,8 +85,7 @@ class Emulator(object):
     def __read_until(self, waitstr, timeout=5):
         data = self.__tn.read_until(waitstr, timeout)
         self.log += data
-        with infra.smart_open(self.log_file) as lfh:
-            lfh.write(data)
+        self.logfile.write(data)
         return data
 
     def __write(self, wstr):
@@ -100,8 +96,7 @@ class Emulator(object):
     def login(self, password=None):
         self.__read_until("buildroot login:", 10)
         if "buildroot login:" not in self.log:
-            with infra.smart_open(self.log_file) as lfh:
-                lfh.write("==> System does not boot")
+            self.logfile.write("==> System does not boot")
             raise SystemError("System does not boot")
 
         self.__write("root\n")