diff --git a/lib/xmet/skew_t.py b/lib/xmet/skew_t.py
index db74adf..86a9211 100644
--- a/lib/xmet/skew_t.py
+++ b/lib/xmet/skew_t.py
@@ -32,11 +32,12 @@ def clamp(value, lowest, highest):
     return value
 
 class SkewTGraph():
-    __slots__ = 'width', 'height', 'temp_step_width',
+    __slots__ = 'width', 'height', 'skew', 'temp_step_width',
 
-    def __init__(self, width: float, height: float):
+    def __init__(self, width: float, height: float, skew: float=SKEW):
         self.width  = width
         self.height = height
+        self.skew   = skew
 
         self.temp_step_width = min(self.width, self.height) / TEMP_STEP_COUNT
 
@@ -74,7 +75,7 @@ class SkewTGraph():
         cr.restore()
 
     def skew_t_to_graph(self, x: float, y: float):
-        return (x+SKEW*y, y)
+        return (x+self.skew*y, y)
 
     def sample_to_graph(self, temp: float, pressure: float):
         x = (temp / TEMP_STEP) * self.temp_step_width
@@ -241,7 +242,7 @@ class SkewTLegend():
             x_rel, y_rel = skew_t.sample_to_screen(temp, PRESSURE_MAX)
 
             if x_rel < 0:
-                y_rel = skew_t.height + x_rel / SKEW
+                y_rel = skew_t.height + x_rel / skew_t.skew
                 x_rel = 0
 
                 if y_rel <= 0: