diff --git a/mercury/app.py b/mercury/app.py
index 6e613d92..2d44560e 100644
--- a/mercury/app.py
+++ b/mercury/app.py
@@ -2,7 +2,6 @@
 import json
 import os
 import shutil
-import subprocess
 import sys
 import tempfile
 
@@ -27,16 +26,12 @@ def send_rabbit_msg(msg, channel, exchange='', routing_key='task_queue'):
     print(" [X] %s UTC %r %r" % (str(datetime.datetime.utcnow()),
                                  str(msg['id']), str(msg['file_path'])))
 
-def run_proc(args, output=subprocess.DEVNULL):
-    proc = subprocess.Popen(args, stdout=output)
-    return proc.communicate()
-
 def run_mercury(path):
     with tempfile.TemporaryDirectory() as tempdir:
         mercury = shutil.which('pmercury')
         mercury_output = os.path.join(tempdir, 'mercury_output.txt')
         args = [mercury, '-awxg', '-r', path, '-f', mercury_output]
-        run_proc(args)
+        network_tools_lib.run_proc(args)
         with open(mercury_output, 'r') as f:
             return f.read()
 
diff --git a/network_tools_lib/network_tools_lib.py b/network_tools_lib/network_tools_lib.py
index 3d536e00..d398a496 100644
--- a/network_tools_lib/network_tools_lib.py
+++ b/network_tools_lib/network_tools_lib.py
@@ -1,4 +1,5 @@
 import os
+import subprocess
 
 
 def mod_path(filename, file_for_dir=None):
@@ -11,3 +12,9 @@ def get_version():
     ver_path = os.path.join(mod_path('VERSION', __file__))
     with open(ver_path, 'r') as f:
         return f.read().strip()
+
+
+def run_proc(args, output=subprocess.DEVNULL):
+    with subprocess.Popen(args, stdout=output) as proc:
+        proc_output = proc.communicate()
+    return proc_output
diff --git a/p0f/app.py b/p0f/app.py
index 39d737a1..afd443de 100644
--- a/p0f/app.py
+++ b/p0f/app.py
@@ -3,7 +3,6 @@
 import logging
 import os
 import shutil
-import subprocess
 import sys
 import tempfile
 
@@ -13,10 +12,6 @@
 VERSION = network_tools_lib.get_version()
 
 
-def run_proc(args, output=subprocess.DEVNULL):
-    proc = subprocess.Popen(args, stdout=output)
-    return proc.communicate()
-
 def run_p0f(path):
     with tempfile.TemporaryDirectory() as tempdir:
         p0f = shutil.which('p0f')
@@ -25,7 +20,7 @@ def run_p0f(path):
             p0f = '/usr/sbin/p0f'
         p0f_output = os.path.join(tempdir, 'p0f_output.txt')
         args = [p0f, '-r', path, '-o', p0f_output]
-        run_proc(args)
+        network_tools_lib.run_proc(args)
         with open(p0f_output, 'r') as f:
             return f.read()
 
diff --git a/p0f/test_app.py b/p0f/test_app.py
index d1f0c9ac..2cbf50e0 100644
--- a/p0f/test_app.py
+++ b/p0f/test_app.py
@@ -5,6 +5,7 @@
 @author: Charlie Lewis
 """
 import os
+import shutil
 import sys
 
 from .app import VERSION
@@ -14,11 +15,17 @@
 from .app import run_tshark
 from .app import run_p0f
 from .app import build_result_json
+import network_tools_lib
 
 
 TEST_LO_CAP = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'test_lo.cap')
 
 
+def test_runproc():
+    # returned filehandles both none as process has exited.
+    assert network_tools_lib.run_proc([shutil.which('ls')]) == (None, None)
+
+
 def test_ispcap():
     assert ispcap('afile.pcap')  # nosec
     assert not ispcap('notapcap.txt')  # nosec