diff --git a/CHANGELOG.md b/CHANGELOG.md
index 68cc609c..bfeb713c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Removed
 
 ### Fixed
+- Don't define `ostream& operator<<(nullptr_t)` if already defined by Apple
 
 ### Security
 
diff --git a/cpp/unittest/OstreamHelpers.h b/cpp/unittest/OstreamHelpers.h
index a2cd8f45..14280d3a 100644
--- a/cpp/unittest/OstreamHelpers.h
+++ b/cpp/unittest/OstreamHelpers.h
@@ -2,4 +2,8 @@
 
 #include <ostream>
 
+#if (defined __apple_build_version__) && (__apple_build_version__ >= 12000000)
+// defined in /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../include/c++/v1/ostream:223:20
+#else
 inline std::ostream& operator << (std::ostream& out, const std::nullptr_t &np) { return out << "nullptr"; }
+#endif