diff --git a/pysd/py_backend/functions.py b/pysd/py_backend/functions.py
index 8c6930dd..8ca97014 100644
--- a/pysd/py_backend/functions.py
+++ b/pysd/py_backend/functions.py
@@ -744,9 +744,9 @@ def _integrate(self, time_steps, capture_elements, return_timestamps):
         return outputs
 
 
-def ramp(slope, start, finish):
+def ramp(slope, start, finish=0):
     """
-    Implements vensim's RAMP function
+    Implements vensim's and xmile's RAMP function
 
     Parameters
     ----------
@@ -755,7 +755,7 @@ def ramp(slope, start, finish):
     start: float
         Time at which the ramp begins
     finish: float
-        Time at which the ramo ends
+        Optional. Time at which the ramp ends
 
     Returns
     -------
@@ -770,10 +770,13 @@ def ramp(slope, start, finish):
     t = time()
     if t < start:
         return 0
-    elif t > finish:
-        return slope * (finish - start)
     else:
-        return slope * (t - start)
+        if finish <= 0:
+            return slope * (t - start)
+        elif t > finish:
+            return slope * (finish - start)
+        else:
+            return slope * (t - start)
 
 
 def step(value, tstep):
diff --git a/pysd/py_backend/xmile/SMILE2Py.py b/pysd/py_backend/xmile/SMILE2Py.py
index 465c8f8d..8be5061f 100644
--- a/pysd/py_backend/xmile/SMILE2Py.py
+++ b/pysd/py_backend/xmile/SMILE2Py.py
@@ -79,8 +79,7 @@
 
     "pulse": "functions.pulse_magnitude",
     "step": "functions.step",
-    
-    # "ramp" !TODO!
+    "ramp" "functions.ramp",
     
     # ===
     # 3.5.5 Time Functions