diff --git a/pymbolic/interop/common.py b/pymbolic/interop/common.py
index 5243a8326605019dc5ad84f631386b7a2848bfee..7b986d8cdb981d9b85c744b93e992d991b2211de 100644
--- a/pymbolic/interop/common.py
+++ b/pymbolic/interop/common.py
@@ -157,8 +157,7 @@ class PymbolicToSympyLikeMapper(EvaluationMapper):
                 )
 
     def map_derivative(self, expr):
-        return self.sym.Derivative(self.rec(expr.child),
-                *[self.sym.Symbol(v) for v in expr.variables])
+        raise NotImplementedError()
 
 # }}}
 
diff --git a/pymbolic/interop/symengine.py b/pymbolic/interop/symengine.py
index 6746f85f2b5e7eb0d74882cd9bf17b2d953bd523..ab68e7fde1596e390ad59e55b40827589d9c6f80 100644
--- a/pymbolic/interop/symengine.py
+++ b/pymbolic/interop/symengine.py
@@ -90,6 +90,10 @@ class PymbolicToSymEngineMapper(PymbolicToSympyLikeMapper):
         raise RuntimeError(
             "do not know how to translate '%s' to symengine" % expr)
 
+    def map_derivative(self, expr):
+        return self.sym.Derivative(self.rec(expr.child),
+                [self.sym.Symbol(v) for v in expr.variables])
+
 # }}}
 
 # vim: fdm=marker
diff --git a/pymbolic/interop/sympy.py b/pymbolic/interop/sympy.py
index 2f538a7858eb0ef10d8610e2ea705f5c6cdd35fe..7e1f4399a6ce0bf21c5931f084e1b1aef6d7c3fc 100644
--- a/pymbolic/interop/sympy.py
+++ b/pymbolic/interop/sympy.py
@@ -73,6 +73,10 @@ class PymbolicToSympyMapper(PymbolicToSympyLikeMapper):
         raise RuntimeError(
             "do not know how to translate '%s' to sympy" % expr)
 
+    def map_derivative(self, expr):
+        return self.sym.Derivative(self.rec(expr.child),
+                *[self.sym.Symbol(v) for v in expr.variables])
+
 # }}}
 
 
diff --git a/test/test_sympy.py b/test/test_sympy.py
index 2286d266ba667bfe60a59c12ffc87612d873a02a..f5d294a55e4efbe4e315e498eed3cebb4e89aa20 100644
--- a/test/test_sympy.py
+++ b/test/test_sympy.py
@@ -37,12 +37,12 @@ except ImportError:
 
 import pymbolic.primitives as prim
 
-x_, y_ = (prim.Variable(s) for s in "xy")
+x_, y_ = (prim.Variable(s) for s in "x y".split())
 
 
 # {{{ to pymbolic test
 
-def _test_to_pymbolic(mapper, sym):
+def _test_to_pymbolic(mapper, sym, use_symengine):
     x, y = sym.symbols("x,y")
 
     assert mapper(sym.Rational(3, 4)) == prim.Quotient(3, 4)
@@ -50,8 +50,9 @@ def _test_to_pymbolic(mapper, sym):
 
     assert mapper(sym.Subs(x**2, (x,), (y,))) == \
         prim.Substitution(x_**2, ("x",), (y_,))
-    assert mapper(sym.Derivative(x**2, x)) == \
-        prim.Derivative(x_**2, ("x",))
+    # FIXME in symengine
+    deriv = sym.Derivative(x**2, (x,)) if use_symengine else sym.Derivative(x**2, x)
+    assert mapper(deriv) == prim.Derivative(x_**2, ("x",))
 
     # functions
     assert mapper(sym.Function("f")(x)) == prim.Variable("f")(x_)
@@ -71,19 +72,19 @@ def test_symengine_to_pymbolic():
     sym = pytest.importorskip("symengine.sympy_compat")
     mapper = SymEngineToPymbolicMapper()
 
-    _test_to_pymbolic(mapper, sym)
+    _test_to_pymbolic(mapper, sym, True)
 
 
 def test_sympy_to_pymbolic():
     import sympy as sym
     mapper = SympyToPymbolicMapper()
 
-    _test_to_pymbolic(mapper, sym)
+    _test_to_pymbolic(mapper, sym, False)
 
 
 # {{{ from pymbolic test
 
-def _test_from_pymbolic(mapper, sym):
+def _test_from_pymbolic(mapper, sym, use_symengine):
     x, y = sym.symbols("x,y")
 
     assert mapper(x_ + y_) == x + y
@@ -92,11 +93,14 @@ def _test_from_pymbolic(mapper, sym):
 
     assert mapper(prim.Substitution(x_**2, ("x",), (y_,))) == \
         sym.Subs(x**2, (x,), (y,))
-    assert mapper(prim.Derivative(x_**2, ("x",))) == \
-        sym.Derivative(x**2, x)
+    # FIXME in symengine
+    deriv = sym.Derivative(x**2, (x,)) if use_symengine else sym.Derivative(x**2, x)
+    assert mapper(prim.Derivative(x_**2, ("x",))) == deriv
 
     assert mapper(x_[0]) == sym.Symbol("x_0")
 
+    assert mapper(prim.Variable("f")(x_)) == sym.Function("f")(x)
+
 # }}}
 
 
@@ -104,14 +108,14 @@ def test_pymbolic_to_symengine():
     sym = pytest.importorskip("symengine.sympy_compat")
     mapper = PymbolicToSymEngineMapper()
 
-    _test_from_pymbolic(mapper, sym)
+    _test_from_pymbolic(mapper, sym, True)
 
 
 def test_pymbolic_to_sympy():
     import sympy as sym
     mapper = PymbolicToSympyMapper()
 
-    _test_from_pymbolic(mapper, sym)
+    _test_from_pymbolic(mapper, sym, False)
 
 
 if __name__ == "__main__":