diff --git a/core/utils.py b/core/utils.py
index 8a450a92..8a55a8a4 100644
--- a/core/utils.py
+++ b/core/utils.py
@@ -33,12 +33,6 @@ def duration_string(duration):
     return duration
 
 
-def duration_string_short(duration):
-    """Format hours, minutes and seconds as a short string (e.g. "0h2m35s")."""
-    h, m, s = duration_parts(duration)
-    return '{}h{}m{}s'.format(h, m, s)
-
-
 def duration_parts(duration):
     """Get hours, minutes and seconds from a timedelta."""
     if not isinstance(duration, timezone.timedelta):
@@ -46,4 +40,4 @@ def duration_parts(duration):
     h, remainder = divmod(duration.seconds, 3600)
     h += duration.days * 24
     m, s = divmod(remainder, 60)
-    return h, m, s
\ No newline at end of file
+    return h, m, s
diff --git a/reports/graphs.py b/reports/graphs.py
index 3bd13150..a0344d2c 100644
--- a/reports/graphs.py
+++ b/reports/graphs.py
@@ -12,7 +12,7 @@ import plotly.offline as plotly
 import plotly.graph_objs as go
 
 from core.models import DiaperChange, Feeding, Sleep, TummyTime
-from core.utils import duration_string, duration_string_short
+from core.utils import duration_string, duration_parts
 
 from .utils import default_graph_layout_options, split_graph_output
 
@@ -87,7 +87,7 @@ def sleep_totals(child):
         y=[td.seconds/3600 for td in totals.values()],
         hoverinfo='text',
         textposition='outside',
-        text=[duration_string_short(td) for td in totals.values()]
+        text=[_duration_string_short(td) for td in totals.values()]
     )
 
     layout_args = default_graph_layout_options()
@@ -104,6 +104,13 @@ def sleep_totals(child):
     return split_graph_output(output)
 
 
+def _duration_string_short(duration):
+    """Format a "short" duration string without seconds precision. This is
+    intended to fit better in smaller spaces on a graph."""
+    h, m, s = duration_parts(duration)
+    return '{}h{}m'.format(h, m)
+
+
 def sleep_pattern(child):
     """Create a graph showing blocked out periods of sleep during each day."""
     # TODO: Simplify this using the bar charts "base" property.