diff --git a/corsika/detail/framework/geometry/QuantityVector.inl b/corsika/detail/framework/geometry/QuantityVector.inl
index c7f9457b98dc0935c710f6d93fef6c53aab69f56..7af47d7e1ea5c468511937da49b522586280ff3d 100644
--- a/corsika/detail/framework/geometry/QuantityVector.inl
+++ b/corsika/detail/framework/geometry/QuantityVector.inl
@@ -102,26 +102,26 @@ namespace corsika {
   }
 
   template <typename TDimension>
-  inline auto& QuantityVector<TDimension>::operator/=(double const p) {
+  inline auto QuantityVector<TDimension>::operator/=(double const p) {
     eigenVector_ /= p;
     return *this;
   }
 
   template <typename TDimension>
-  inline auto& QuantityVector<TDimension>::operator*=(double const p) {
+  inline auto QuantityVector<TDimension>::operator*=(double const p) {
     eigenVector_ *= p;
     return *this;
   }
 
   template <typename TDimension>
-  inline auto& QuantityVector<TDimension>::operator+=(
+  inline auto QuantityVector<TDimension>::operator+=(
       QuantityVector<TDimension> const& pQVec) {
     eigenVector_ += pQVec.eigenVector_;
     return *this;
   }
 
   template <typename TDimension>
-  inline auto& QuantityVector<TDimension>::operator-=(
+  inline auto QuantityVector<TDimension>::operator-=(
       QuantityVector<TDimension> const& pQVec) {
     eigenVector_ -= pQVec.eigenVector_;
     return *this;
diff --git a/corsika/framework/geometry/QuantityVector.hpp b/corsika/framework/geometry/QuantityVector.hpp
index ac7afc51e96e6a0cc4a4a59b8102c3accbb0c476..57d09c29eb5c4684ead155ba2d8a7546f99abf6c 100644
--- a/corsika/framework/geometry/QuantityVector.hpp
+++ b/corsika/framework/geometry/QuantityVector.hpp
@@ -81,11 +81,11 @@ namespace corsika {
 
     auto operator/(double const p) const;
 
-    auto& operator/=(double const p);
+    auto operator/=(double const p);
 
-    auto& operator*=(double const p);
+    auto operator*=(double const p);
 
-    auto& operator+=(QuantityVector<TDimension> const& pQVec);
+    auto operator+=(QuantityVector<TDimension> const& pQVec);
 
     auto& operator-=(QuantityVector<TDimension> const& pQVec);