diff --git a/gwsumm/plot/core.py b/gwsumm/plot/core.py
index bf377d3d..b7480782 100644
--- a/gwsumm/plot/core.py
+++ b/gwsumm/plot/core.py
@@ -21,7 +21,6 @@
 for GWSumm
 """
 
-import hashlib
 import os.path
 import re
 import warnings
@@ -338,8 +337,7 @@ def pid(self):
             filts = "".join(map(str, [
                 getattr(c, 'filter', getattr(c, 'frequency_response', ''))
                 for c in self.channels]))
-            h = (chans + filts).encode('utf-8')
-            self._pid = hashlib.md5(h).hexdigest()[:6]
+            self._pid = putils.hash(chans + filts)
             return self.pid
 
     @pid.setter
diff --git a/gwsumm/plot/range.py b/gwsumm/plot/range.py
index 3e61ba26..374d1cd8 100644
--- a/gwsumm/plot/range.py
+++ b/gwsumm/plot/range.py
@@ -22,7 +22,6 @@
 from __future__ import division
 
 import re
-import hashlib
 from math import pi
 
 from six import string_types
@@ -35,6 +34,7 @@
 from gwpy.timeseries import TimeSeries
 
 from .registry import (get_plot, register_plot)
+from .utils import hash
 from ..data import (get_range_channel, get_range, get_timeseries)
 from ..segments import get_segments
 from ..channels import split as split_channels
@@ -146,8 +146,7 @@ def pid(self):
         try:
             return self._pid
         except:
-            chans = "".join(map(str, self.channels+self.flags))
-            self._pid = hashlib.md5(chans).hexdigest()[:6]
+            self._pid = hash("".join(map(str, self.channels+self.flags)))
             return self.pid
 
     @pid.setter
diff --git a/gwsumm/plot/segments.py b/gwsumm/plot/segments.py
index 79343109..f1f547f6 100644
--- a/gwsumm/plot/segments.py
+++ b/gwsumm/plot/segments.py
@@ -21,7 +21,6 @@
 
 from __future__ import division
 
-import hashlib
 import bisect
 from itertools import (cycle, combinations)
 from numbers import Number
@@ -61,7 +60,7 @@
 from .core import (BarPlot, PiePlot, format_label)
 from .registry import (get_plot, register_plot)
 from .mixins import SegmentLabelSvgMixin
-from .utils import usetex_tex
+from .utils import (hash, usetex_tex)
 
 __author__ = 'Duncan Macleod <duncan.macleod@ligo.org>'
 
@@ -191,8 +190,7 @@ def pid(self):
         try:
             return self._pid
         except AttributeError:
-            self._pid = hashlib.md5(
-                "".join(map(str, self.flags))).hexdigest()[:6]
+            self._pid = hash("".join(map(str, self.flags)))
             return self.pid
 
     @pid.setter
@@ -406,11 +404,10 @@ def pid(self):
         try:
             return self._pid
         except:
-            chans = "".join(map(str, self.channels))
-            self._pid = hashlib.md5(chans).hexdigest()[:6]
+            basis = "".join(map(str, self.channels))
             if self.pargs.get('bits', None):
-                self._pid = hashlib.md5(
-                    self._pid + str(self.pargs['bits'])).hexdigest()[:6]
+                basis += str(self.pargs['bits'])
+            self._pid = hash(basis)
             return self.pid
 
     def _parse_labels(self, defaults=[]):
@@ -838,10 +835,10 @@ def pid(self):
         except:
             chans = "".join(map(str, self.channels))
             masks = "".join(map(str, self.get_bitmask_channels()))
-            self._pid = hashlib.md5(chans+masks).hexdigest()[:6]
+            basis = chans + masks
             if self.pargs.get('bits', None):
-                self._pid = hashlib.md5(
-                    self._pid + str(self.pargs['bits'])).hexdigest()[:6]
+                basis += str(self.pargs["bits"])
+            self._pid = hash(basis)
             return self.pid
 
     def draw(self):
diff --git a/gwsumm/plot/triggers.py b/gwsumm/plot/triggers.py
index a7466395..32041fec 100644
--- a/gwsumm/plot/triggers.py
+++ b/gwsumm/plot/triggers.py
@@ -21,7 +21,6 @@
 
 from __future__ import division
 
-import hashlib
 import re
 from collections import OrderedDict
 from itertools import cycle
@@ -42,7 +41,7 @@
 from ..data import (get_channel, get_timeseries, add_timeseries)
 from ..triggers import (get_triggers, get_time_column)
 from .registry import (get_plot, register_plot)
-from .utils import (get_column_string, usetex_tex)
+from .utils import (get_column_string, hash, usetex_tex)
 
 __author__ = 'Duncan Macleod <duncan.macleod@ligo.org>'
 
@@ -80,8 +79,8 @@ def pid(self):
                 getattr(c, 'filter', getattr(c, 'frequency_response', ''))
                 for c in self.channels]))
             if self.filterstr:
-                filts = "".join([filts, self.filterstr])
-            self._pid = hashlib.md5(chans+filts).hexdigest()[:6]
+                filts += self.filterstr
+            self._pid = hash(chans + filts)
             return self.pid
 
 
diff --git a/gwsumm/plot/utils.py b/gwsumm/plot/utils.py
index 597efc07..af20b280 100644
--- a/gwsumm/plot/utils.py
+++ b/gwsumm/plot/utils.py
@@ -19,6 +19,7 @@
 """Utilies for GWSumm plotting
 """
 
+import hashlib
 import itertools
 import re
 
@@ -151,3 +152,28 @@ def usetex_tex(text):
     if rcParams['text.usetex']:
         return label_to_latex(text)
     return text
+
+
+def hash(string, num=6):
+    """Generate an N-character hash string based using string to initialise
+
+    Parameters
+    ----------
+    string : `str`
+        the initialisation string
+
+    num : `int`, optional
+        the length of the hash to produce
+
+    Returns
+    -------
+    hash : `str`
+        the new hash
+
+    Examples
+    --------
+    >>> from gwsumm.plot.utils import hash
+    >>> print(hash("I love gravitational waves"))
+    80c897
+    """
+    return hashlib.md5(string.encode("utf-8")).hexdigest()[:num]