diff --git a/artist/graph_artist.py b/artist/graph_artist.py
index <HASH>..<HASH> 100644
--- a/artist/graph_artist.py
+++ b/artist/graph_artist.py
@@ -1,10 +1,12 @@
-import jinja2
 import subprocess
 import os
 import tempfile
 import shutil
 from itertools import izip_longest
 
+import jinja2
+import numpy as np
+
 
 class GraphArtist:
     def __init__(self, axis='', width=r'.67\linewidth', height=None):
@@ -53,7 +55,7 @@ class GraphArtist:
     def set_title(self, text):
         self.title = text
 
-    def add_pin(self, text, location='left', use_arrow=False,
+    def add_pin(self, text, x=None, location='left', use_arrow=False,
                 relative_position=None):
         """Add pin to most recent data series"""
 
@@ -64,7 +66,13 @@ class GraphArtist:
                 First plot a data series, before using this function""")
 
         data = series['data']
-        x, y = zip(*data)[:2]
+        series_x, series_y = zip(*data)[:2]
+
+        if x is not None:
+            y = np.interp(x, series_x, series_y)
+        else:
+            x, y = series_x, series_y
+
         self.add_pin_at_xy(x, y, text, location, relative_position,
                            use_arrow)
add_pin method: new option x

You can now specify a pin at a specific x location.  For example, if you
have a data series (x, y), you can add a pin at x = <I>.  The pin location
will be interpolated, so you need not have a x = <I> in your data series.