diff --git a/Lib/fontTools/varLib/instancer/solver.py b/Lib/fontTools/varLib/instancer/solver.py
index 29e6baffe..6d61c83cc 100644
--- a/Lib/fontTools/varLib/instancer/solver.py
+++ b/Lib/fontTools/varLib/instancer/solver.py
@@ -145,7 +145,8 @@ def _solve(tent, axisLimit):
 def rebaseTent(tent, axisLimit):
     """Given a tuple (lower,peak,upper) "tent" and new axis limits
     (axisMin,axisDefault,axisMax), solves how to represent the tent
-    under the new axis configuration.
+    under the new axis configuration.  All values are in normalized
+    -1,0,+1 coordinate system. Tent values can be outside this range.
 
     Return value is a list of tuples. Each tuple is of the form
     (scalar,tent), where scalar is a multipler to multiply any