diff --git a/include/DiscreteAngle.h b/include/DiscreteAngle.h
index 17c4616..5a2171b 100644
--- a/include/DiscreteAngle.h
+++ b/include/DiscreteAngle.h
@@ -8,7 +8,7 @@ class DiscreteAngle16 : public Range16 {
 public:
   DiscreteAngle16(float angle);
 
-  inline DiscreteAngle16 &operator-();
+  inline DiscreteAngle16 &operator-() override;
 };
 
 #endif
\ No newline at end of file
diff --git a/include/Range.h b/include/Range.h
index f66bcf0..e73cde7 100644
--- a/include/Range.h
+++ b/include/Range.h
@@ -10,7 +10,7 @@ public:
 
   inline Range16 operator-(Range16 a);
   inline Range16 operator+(Range16 a);
-  inline Range16 &operator-();
+  inline virtual Range16 &operator-();
 
   inline bool operator==(Range16 a);
   inline bool operator!=(Range16 a);