diff --git a/include/armadillo_bits/SpBase_bones.hpp b/include/armadillo_bits/SpBase_bones.hpp
index 137de447..f8426109 100644
--- a/include/armadillo_bits/SpBase_bones.hpp
+++ b/include/armadillo_bits/SpBase_bones.hpp
@@ -54,9 +54,9 @@ struct SpBase
   
   arma_inline bool is_alias(const SpMat<elem_type>& X) const;
   
-  inline const SpOp<derived,spop_htrans>  t() const;  //!< Hermitian transpose
-  inline const SpOp<derived,spop_htrans> ht() const;  //!< Hermitian transpose
-  inline const SpOp<derived,spop_strans> st() const;  //!< simple transpose
+  inline arma_warn_unused const SpOp<derived,spop_htrans>  t() const;  //!< Hermitian transpose
+  inline arma_warn_unused const SpOp<derived,spop_htrans> ht() const;  //!< Hermitian transpose
+  inline arma_warn_unused const SpOp<derived,spop_strans> st() const;  //!< simple transpose
   
   arma_cold inline void print(                           const std::string extra_text = "") const;
   arma_cold inline void print(std::ostream& user_stream, const std::string extra_text = "") const;
diff --git a/include/armadillo_bits/SpBase_meat.hpp b/include/armadillo_bits/SpBase_meat.hpp
index 3fc87cc6..e98b1218 100644
--- a/include/armadillo_bits/SpBase_meat.hpp
+++ b/include/armadillo_bits/SpBase_meat.hpp
@@ -43,6 +43,7 @@ SpBase<elem_type,derived>::is_alias(const SpMat<elem_type>& X) const
 
 template<typename elem_type, typename derived>
 inline
+arma_warn_unused
 const SpOp<derived, spop_htrans>
 SpBase<elem_type,derived>::t() const
   {
@@ -52,6 +53,7 @@ SpBase<elem_type,derived>::t() const
 
 template<typename elem_type, typename derived>
 inline
+arma_warn_unused
 const SpOp<derived, spop_htrans>
 SpBase<elem_type,derived>::ht() const
   {
@@ -62,6 +64,7 @@ SpBase<elem_type,derived>::ht() const
 
 template<typename elem_type, typename derived>
 inline
+arma_warn_unused
 const SpOp<derived, spop_strans>
 SpBase<elem_type,derived>::st() const
   {