diff --git a/src/PenningTrap.cpp b/src/PenningTrap.cpp
index 7a4ff2b..23e1b80 100644
--- a/src/PenningTrap.cpp
+++ b/src/PenningTrap.cpp
@@ -9,7 +9,6 @@
  *
  *  @bug No known bugs
  *
- *  @todo Implement constructor
  *  @todo Implement add_particle
  *  @todo Implement external_E_field
  *  @todo Implement external_B_field
@@ -25,7 +24,9 @@
 
 PenningTrap::PenningTrap(double B_0, double V_0, double d)
 {
-
+    this->B_0 = B_0;
+    this->V_0 = V_0;
+    this->d = d;
 }
 
 void PenningTrap::add_particle(Particle particle)