diff --git a/include/units/Angle.hpp b/include/units/Angle.hpp
index 5c5d815..4468d2e 100644
--- a/include/units/Angle.hpp
+++ b/include/units/Angle.hpp
@@ -59,15 +59,17 @@ class CAngle {
         // make CAngle able to be implicitly converted to Angle
         constexpr operator Angle() const { return Angle(M_PI_2 - this->value); }
 
-        constexpr Angle operator-() const { return CAngle(-this->value); }
+        constexpr CAngle operator-() const { return CAngle(-this->value); }
 
-        constexpr Angle operator+() const { return CAngle(this->value); }
+        constexpr CAngle operator+() const { return CAngle(this->value); }
     private:
         const double value;
 
         constexpr CAngle(double value) : value(value) {}
 };
 
+constexpr bool operator==(Angle lhs, CAngle rhs) { return lhs == Angle(rhs); }
+
 constexpr Angle rad = Angle(1.0);
 constexpr Angle deg = Angle(M_PI / 180);
 constexpr Angle rot = Angle(M_TWOPI);
diff --git a/src/main.cpp b/src/main.cpp
index 3497b55..bc565e5 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -47,7 +47,7 @@ void initialize() {
 
 void angleTests() {
     static_assert(+15_cDeg == 75_stDeg);
-    static_assert(to_stDeg(-15_cDeg) == to_stDeg(105_stDeg));
+    static_assert(to_stDeg(-+15_cDeg) == to_stDeg(105_stDeg));
     static_assert(r2i(to_stDeg(30_cDeg)) == r2i(to_stDeg(60_stDeg)));
     static_assert(r2i(to_stDeg(+0_cDeg)) == r2i(to_stDeg(90_stDeg)));
     Angle a = 2_cDeg;