diff --git a/mutation_partition.cc b/mutation_partition.cc
index 14406b6ae8..1836d095c3 100644
--- a/mutation_partition.cc
+++ b/mutation_partition.cc
@@ -349,7 +349,7 @@ operator<<(std::ostream& os, const row::value_type& rv) {
 
 std::ostream&
 operator<<(std::ostream& os, const row& r) {
-    return fprint(os, "{row: %s}", ::join(", ", r));
+    return fprint(os, "{row: %s}", ::join(", ", r._cells));
 }
 
 std::ostream&
diff --git a/mutation_partition.hh b/mutation_partition.hh
index 414d55454b..e7f65620c4 100644
--- a/mutation_partition.hh
+++ b/mutation_partition.hh
@@ -162,10 +162,11 @@ public:
     }
 
     bool operator==(const row&) const;
+
+    friend std::ostream& operator<<(std::ostream& os, const row& r);
 };
 
 std::ostream& operator<<(std::ostream& os, const row::value_type& rv);
-std::ostream& operator<<(std::ostream& os, const row& r);
 
 class row_marker {
     static constexpr gc_clock::duration no_ttl { 0 };