diff --git a/gtsam/basis/Chebyshev2.h b/gtsam/basis/Chebyshev2.h
index 25974adfd0..0c253fb75e 100644
--- a/gtsam/basis/Chebyshev2.h
+++ b/gtsam/basis/Chebyshev2.h
@@ -88,7 +88,7 @@ class GTSAM_EXPORT Chebyshev2 : public Basis<Chebyshev2> {
 
   /// Return a zero initialized Parameter matrix.
   static Parameters ParameterMatrix(size_t N) {
-    return Parameters::Zero(N + 1);
+    return Parameters::Zero(N);
   }
 
   /**