diff --git a/include/etr_bits/Allocation.hpp b/include/etr_bits/Allocation.hpp
index e04d050..df87c05 100644
--- a/include/etr_bits/Allocation.hpp
+++ b/include/etr_bits/Allocation.hpp
@@ -5,6 +5,7 @@
 #include "Allocation/Colon.hpp"
 #include "Allocation/Matrix.hpp"
 #include "Allocation/Rep.hpp"
+#include "Allocation/ScalarForDeriv.hpp"
 #include "Allocation/Vector.hpp"
 
-#endif
\ No newline at end of file
+#endif
diff --git a/include/etr_bits/Allocation/ScalarForDeriv.hpp b/include/etr_bits/Allocation/ScalarForDeriv.hpp
new file mode 100644
index 0000000..4eab175
--- /dev/null
+++ b/include/etr_bits/Allocation/ScalarForDeriv.hpp
@@ -0,0 +1,19 @@
+#ifndef SCALAR_DERIV_ETR_H
+#define SCALAR_DERIV_ETR_H
+
+#include "../Core.hpp"
+
+namespace etr {
+
+template <int Idx, typename AV, typename T>
+  requires std::is_arithmetic_v<T>
+inline auto scalarDeriv(AV &av, T s) {
+  av.varConstants[Idx].resize(1);
+  av.varConstants[Idx][0] = s;
+  Vec<T, VarPointer<decltype(av), Idx, -1>, ConstantTypeTrait> ret(av);
+  return ret;
+}
+
+} // namespace etr
+
+#endif
diff --git a/tests/Derivatives_Tests.cpp b/tests/Derivatives_Tests.cpp
index 8a79c13..a076695 100644
--- a/tests/Derivatives_Tests.cpp
+++ b/tests/Derivatives_Tests.cpp
@@ -33,7 +33,7 @@ int main() {
   // NOTE: test minus
   {
     std::cout << "test minus" << std::endl;
-    AllVars<2, 0, 0, 2> av(0, 0);
+    AllVars<2, 0, 0, 3> av(0, 0);
     Vec<double, VarPointer<decltype(av), 0, 0>, VariableTypeTrait> a(av);
     Vec<double, VarPointer<decltype(av), 1, 0>, VariableTypeTrait> b(av);
 
@@ -69,7 +69,7 @@ int main() {
 
     std::cout << "\n"
               << "a = a / b" << std::endl;
-    a = a / b;
+    a = a / scalarDeriv<3>(av, 3.14);
     print(a, av);
     print(b, av);
     print(get_derivs(a));