diff --git a/dice/core/constraint.py b/dice/core/constraint.py
index f807036..7bfae08 100644
--- a/dice/core/constraint.py
+++ b/dice/core/constraint.py
@@ -286,8 +286,7 @@ def apply(self, item):
         """
         def _name2path(name):
             if not name.startswith(self.path_prefix):
-                raise ConstraintError(
-                    "Solution %s is not a path variable" % name)
+                return name
             return name[len(self.path_prefix):].replace('_', '/')
 
         t = self._choose()
diff --git a/dice/core/trace.py b/dice/core/trace.py
index fc34eb0..30733ac 100644
--- a/dice/core/trace.py
+++ b/dice/core/trace.py
@@ -45,6 +45,8 @@ def __repr__(self):
         for line in self.trace:
             if isinstance(line, ast.Compare):
                 s = str(line.ops[0].__class__.__name__)
+            elif isinstance(line, ast.Call):
+                s = line.func.id
             else:
                 s = line.value.func.id
             lines.append(s)
diff --git a/examples/pyramid/oracles/pyramid.yaml b/examples/pyramid/oracles/pyramid.yaml
index bb701b3..6543635 100644
--- a/examples/pyramid/oracles/pyramid.yaml
+++ b/examples/pyramid/oracles/pyramid.yaml
@@ -1,14 +1,13 @@
 - name: option
-  target: option
-  tree: |
-      if self is Integer:
-          if self < 0:
+  oracle: |
+      if option is Integer:
+          if option < 0:
               return FAIL('Min input is 0')
-          elif self > 9223372036854775808:
+          elif option > 9223372036854775808:
               return FAIL('Number overflow')
-          elif self > 1000:
+          elif option > 1000:
               return FAIL('Max input is 1000')
           else:
-              return PASS()
+              return SUCCESS()
       else:
           return FAIL('Invalid number')
diff --git a/tox.ini b/tox.ini
index c05e22c..3f0966f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -32,3 +32,4 @@ commands =
 deps =
     -rrequirements.txt
     sphinx
+    sphinx_rtd_theme