diff --git a/README.md b/README.md
index 1c1044d..01a1c51 100644
--- a/README.md
+++ b/README.md
@@ -81,6 +81,10 @@ pub fn main() {
 }
 ```
 
+Use Erlang 27 or later for the best IEEE 754 compliance. Earlier versions will
+work for the vast majority of use cases, but operations involving or returning
+negative zero may return non-compliant results.
+
 ## License
 
 This library is published under the MIT license, a copy of which is included.