diff --git a/cpp/sophus/linalg/homogeneous.h b/cpp/sophus/linalg/homogeneous.h
index 4c1eb0fc..91ee26c2 100644
--- a/cpp/sophus/linalg/homogeneous.h
+++ b/cpp/sophus/linalg/homogeneous.h
@@ -29,7 +29,8 @@ auto proj(Eigen::MatrixBase<TPoint> const& p)
 /// point: (z*a, z*b, z). Z defaults to 1.
 template <class TPoint>
 auto unproj(
-    Eigen::MatrixBase<TPoint> const& p, const typename TPoint::Scalar& z = 1.0)
+    Eigen::MatrixBase<TPoint> const& p,
+    const typename TPoint::Scalar& z = typename TPoint::Scalar(1.0))
     -> Eigen::Vector<typename TPoint::Scalar, TPoint::RowsAtCompileTime + 1> {
   using Scalar = typename TPoint::Scalar;
   static_assert(TPoint::ColsAtCompileTime == 1, "p must be a column-vector");