diff --git a/tools/pylib/boutdata/collect.py b/tools/pylib/boutdata/collect.py
index 1058108592..e56140d0d6 100644
--- a/tools/pylib/boutdata/collect.py
+++ b/tools/pylib/boutdata/collect.py
@@ -136,7 +136,7 @@ def getDataFile(i):
             ystart = 0
             ylim = None
         else:
-            ystart = mxg
+            ystart = myg
             if myg > 0:
                 ylim = -myg
             else: