diff --git a/src/Classic/Solvers/CollimatorPhysics.cpp b/src/Classic/Solvers/CollimatorPhysics.cpp
index 9f5d7879e99bcb2bec894ba00b8e2bb9a4a81443..797e1f7dbdb741215cf630dc4d7250de41ccf3fb 100644
--- a/src/Classic/Solvers/CollimatorPhysics.cpp
+++ b/src/Classic/Solvers/CollimatorPhysics.cpp
@@ -54,6 +54,7 @@ CollimatorPhysics::CollimatorPhysics(const std::string &name, ElementBase *eleme
 
     gsl_rng_env_setup();
     rGen_m = gsl_rng_alloc(gsl_rng_default);
+    gsl_rng_set(rGen_m, Options::seed);
 
     Material();
 
@@ -1192,4 +1193,4 @@ void CollimatorPhysics::deleteParticleFromLocalVectorDKS() {
 
 }
 
-#endif
\ No newline at end of file
+#endif