diff --git a/include/loot/exception/cyclic_interaction_error.h b/include/loot/exception/cyclic_interaction_error.h
index 8c195fc7..dea19fde 100644
--- a/include/loot/exception/cyclic_interaction_error.h
+++ b/include/loot/exception/cyclic_interaction_error.h
@@ -51,7 +51,7 @@ public:
    *          has an edge going to the first Vertex.
    * @return A vector of Vertex elements representing the cyclic path.
    */
-  LOOT_API std::vector<Vertex> GetCycle();
+  LOOT_API std::vector<Vertex> GetCycle() const;
 
 private:
   std::vector<Vertex> cycle_;
diff --git a/src/api/sorting/cyclic_interaction_error.cpp b/src/api/sorting/cyclic_interaction_error.cpp
index 9d0367d2..952b2ad1 100644
--- a/src/api/sorting/cyclic_interaction_error.cpp
+++ b/src/api/sorting/cyclic_interaction_error.cpp
@@ -48,5 +48,5 @@ CyclicInteractionError::CyclicInteractionError(std::vector<Vertex> cycle) :
     std::runtime_error("Cyclic interaction detected: " + describeCycle(cycle)),
     cycle_(cycle) {}
 
-std::vector<Vertex> CyclicInteractionError::GetCycle() { return cycle_; }
+std::vector<Vertex> CyclicInteractionError::GetCycle() const { return cycle_; }
 }