diff --git a/light9/Submaster.py b/light9/Submaster.py
--- a/light9/Submaster.py
+++ b/light9/Submaster.py
@@ -271,11 +271,11 @@ def fullsub(*chans):
 # a global instance of Submasters, created on demand
 _submasters = None
 
-def get_global_submasters():
-    """Get (and make on demand) the global instance of Submasters"""
+def get_global_submasters(graph):
+    """Get (and make on demand) the global instance of Submasters."""
     global _submasters
     if _submasters is None:
-        _submasters = Submasters()
+        _submasters = Submasters(graph)
     return _submasters
 
 def get_sub_by_name(name, submasters=None):
diff --git a/light9/curvecalc/subterm.py b/light9/curvecalc/subterm.py
--- a/light9/curvecalc/subterm.py
+++ b/light9/curvecalc/subterm.py
@@ -71,11 +71,14 @@ exprglo = Expr()
         
 class Subexpr:
     curveset = None
-    def __init__(self,curveset,expr=""):
+    def __init__(self,curveset,expr="",graph=None):
         self.curveset = curveset
         self.lasteval = None
-        self.expr=expr
+        self.expr = expr
+        self.graph = graph
         self._smooth_random_items = [random.random() for x in range(100)]
+        self.submasters = Submaster.get_global_submasters(self.graph)
+
     def eval(self,t):
         if self.expr=="":
             dispatcher.send("expr_error",sender=self,exc="no expr, using 0")
@@ -84,6 +87,7 @@ class Subexpr:
         glo['t'] = t
 
         glo = exprglo.exprGlobals(glo, t)
+        glo['getsub'] = lambda name: self.submasters.get_sub_by_name(name)
         
         try:
             self.lasteval = eval(self.expr,glo)
diff --git a/light9/curvecalc/subtermview.py b/light9/curvecalc/subtermview.py
--- a/light9/curvecalc/subtermview.py
+++ b/light9/curvecalc/subtermview.py
@@ -68,7 +68,7 @@ def add_one_subterm(graph, subUri, curve
         expr = '%s(t)' % subname
 
     term = Subterm(Submaster.Submaster(graph=graph, name=subname, sub=subUri),
-                   Subexpr(curveset, expr))
+                   Subexpr(curveset, expr, graph))
     subterms.append(term)
 
     stv = Subtermview(graph, term)