diff --git a/src/ai/default/recruitment.cpp b/src/ai/default/recruitment.cpp
index e1437ff9b99fa..d6bc53cce26fc 100644
--- a/src/ai/default/recruitment.cpp
+++ b/src/ai/default/recruitment.cpp
@@ -40,6 +40,7 @@
 #include "units/filter.hpp"
 #include "units/map.hpp"
 #include "units/types.hpp"
+#include "units/unit.hpp"
 #include "variable.hpp"
 #include "wml_exception.hpp"
 
@@ -103,6 +104,20 @@ const static double COMBAT_CACHE_TOLERANCY = 0.5;
 const static double VILLAGE_PER_SCOUT_MULTIPLICATOR = 2.;
 }
 
+std::string data::to_string() const {
+	std::stringstream s;
+	s << "---------------Content of leader data---------------\n";
+	s << "For leader: " << leader->name() << "\n";
+	s << "ratio_score: " << ratio_score << "\n";
+	s << "recruit_count: " << recruit_count << "\n\n";
+	for (const score_map::value_type& entry : scores) {
+		s << std::setw(20) << entry.first <<
+				" score: " << std::setw(7) << entry.second << "\n";
+	}
+	s << "----------------------------------------------------\n";
+	return s.str();
+}
+
 recruitment::recruitment(rca_context& context, const config& cfg)
 		: candidate_action(context, cfg),
 		  important_hexes_(),
diff --git a/src/ai/default/recruitment.hpp b/src/ai/default/recruitment.hpp
index 6787b6ce6cf89..607de2239a1cb 100644
--- a/src/ai/default/recruitment.hpp
+++ b/src/ai/default/recruitment.hpp
@@ -22,7 +22,6 @@
 
 #include "ai/composite/aspect.hpp"
 #include "ai/composite/rca.hpp"
-#include "units/unit.hpp"
 #include "units/map.hpp"
 
 #include <iomanip>
@@ -84,19 +83,7 @@ struct data {
 		}
 		return normalized;
 	}
-	std::string to_string() const {
-		std::stringstream s;
-		s << "---------------Content of leader data---------------\n";
-		s << "For leader: " << leader->name() << "\n";
-		s << "ratio_score: " << ratio_score << "\n";
-		s << "recruit_count: " << recruit_count << "\n\n";
-		for (const score_map::value_type& entry : scores) {
-			s << std::setw(20) << entry.first <<
-					" score: " << std::setw(7) << entry.second << "\n";
-		}
-		s << "----------------------------------------------------\n";
-		return s.str();
-	}
+	std::string to_string() const;
 };
 
 struct cached_combat_value {