diff --git a/include/lol/private/types/real.h b/include/lol/private/types/real.h
index 7eb6ea59..a9aa6221 100644
--- a/include/lol/private/types/real.h
+++ b/include/lol/private/types/real.h
@@ -157,6 +157,7 @@ public:
     template<typename U> friend real_t<U> fract(real_t<U> const &x);
     template<typename U> friend real_t<U> degrees(real_t<U> const &x);
     template<typename U> friend real_t<U> radians(real_t<U> const &x);
+    template<typename U> friend int sign(real_t<U> const &x);
 
     // Additional functions
     template<typename U> friend real_t<U> franke(real_t<U> const &x,
diff --git a/include/lol/private/types/real.ipp b/include/lol/private/types/real.ipp
index 867068fd..40b2abfa 100644
--- a/include/lol/private/types/real.ipp
+++ b/include/lol/private/types/real.ipp
@@ -1007,6 +1007,11 @@ template<typename T> real_t<T> radians(real_t<T> const &x)
     return x * mul;
 }
 
+template<typename T> int sign(real_t<T> const &x)
+{
+    return x.is_zero() ? 0 : x.is_negative() ? -1 : 1;
+}
+
 template<typename T> real_t<T> fast_log(real_t<T> const &x)
 {
     /* This fast log method is tuned to work on the [1..2] range and