diff --git a/include/PenningTrap.hpp b/include/PenningTrap.hpp
index c6f142b..3afcde8 100644
--- a/include/PenningTrap.hpp
+++ b/include/PenningTrap.hpp
@@ -23,11 +23,6 @@
 #pragma omp declare reduction(+ : vec_3d : omp_out += omp_in)                  \
     initializer(omp_priv = omp_orig)
 
-typedef struct simulation {
-    sim_arr r_vecs;
-    sim_arr v_vecs;
-} simulation_t;
-
 /** @brief A class that simulates a Penning trap.
  *
  *  This class simulates a Penning trap. It can take in a number of particles
diff --git a/include/typedefs.hpp b/include/typedefs.hpp
index de732f6..a5154b8 100644
--- a/include/typedefs.hpp
+++ b/include/typedefs.hpp
@@ -35,4 +35,11 @@ typedef std::vector<sim_cols> sim_arr;
  * */
 typedef arma::vec::fixed<3> vec_3d;
 
+/** @brief Typedef for PenningTrap::simulation return value.
+ * */
+typedef struct simulation {
+    sim_arr r_vecs;
+    sim_arr v_vecs;
+} simulation_t;
+
 #endif