diff --git a/tests/src/unit-alt-string.cpp b/tests/src/unit-alt-string.cpp
index 5ea4e998a..e29a897df 100644
--- a/tests/src/unit-alt-string.cpp
+++ b/tests/src/unit-alt-string.cpp
@@ -161,7 +161,7 @@ class alt_string
   private:
     std::string str_impl {};
 
-    friend bool ::operator<(const char* /*op1*/, const alt_string& /*op2*/) noexcept;
+    friend bool operator<(const char* /*op1*/, const alt_string& /*op2*/) noexcept;
 };
 
 void int_to_string(alt_string& target, std::size_t value)