diff --git a/src/shamira/condensed.py b/src/shamira/condensed.py
--- a/src/shamira/condensed.py
+++ b/src/shamira/condensed.py
@@ -27,7 +27,7 @@ for i in range(256):
 	L[acc] = i
 	acc = gfmul(acc, g)
 L[1] = 0
-inv = [E[255-L[i]] if i!=0 else None for i in range(256)]  # multiplicative inverse
+INV = [E[255-L[i]] if i!=0 else None for i in range(256)]  # multiplicative inverse
 
 
 def get_constant_coef(*points):
@@ -42,7 +42,7 @@ def get_constant_coef(*points):
 		for j in range(k):
 			if i==j: continue
 			(xj, yj) = points[j]
-			prod = gfmul(prod, (gfmul(xj, inv[xj^x])))
+			prod = gfmul(prod, (gfmul(xj, INV[xj^x])))
 		res ^= gfmul(y, prod)
 	return res