diff --git a/changelog b/changelog
index 4d33387fd36..bb19d36cbc6 100644
--- a/changelog
+++ b/changelog
@@ -17,6 +17,8 @@ Version 1.11.10+dev:
    * Changed: Updated valgrind suppression file.
    * Labels are now removed when shroud/fog is removed, rather than waiting
      for a new turn (bug #21434).
+   * Percent signs show when describing traits that increase damage or attacks
+     by a percentage (bug #21577).
 
 Version 1.11.10:
  * Add-ons client:
diff --git a/players_changelog b/players_changelog
index 783afd7fafa..dad82c9eca2 100644
--- a/players_changelog
+++ b/players_changelog
@@ -18,6 +18,8 @@ Version 1.11.10+dev:
    * Units can no longer be moved in linger mode (bug #21450).
    * Labels are now removed when shroud/fog is removed, rather than waiting
      for a new turn (bug #21434).
+   * Percent signs show when describing traits that increase damage or attacks
+     by a percentage (bug #21577).
 
 
 Version 1.11.10:
diff --git a/src/unit_types.cpp b/src/unit_types.cpp
index e706c38f929..b9bd65e94f3 100644
--- a/src/unit_types.cpp
+++ b/src/unit_types.cpp
@@ -245,7 +245,7 @@ bool attack_type::apply_modification(const config& cfg,std::string* description)
 
 		if(description != NULL) {
 			int inc_damage = lexical_cast<int>(increase_damage);
-			desc << utils::signed_value(inc_damage) << " "
+			desc << utils::print_modifier(increase_damage) << " "
 				 << _n("damage","damage", inc_damage);
 		}
 	}
@@ -256,7 +256,7 @@ bool attack_type::apply_modification(const config& cfg,std::string* description)
 
 		if(description != NULL) {
 			int inc_attacks = lexical_cast<int>(increase_attacks);
-			desc << utils::signed_value(inc_attacks) << " "
+			desc << utils::print_modifier(increase_attacks) << " "
 				 << _n("strike", "strikes", inc_attacks);
 		}
 	}
@@ -326,13 +326,13 @@ bool attack_type::describe_modification(const config& cfg,std::string* descripti
 
 		if(increase_damage.empty() == false) {
 			int inc_damage = lexical_cast<int>(increase_damage);
-			desc << utils::signed_value(inc_damage) << " "
+			desc << utils::print_modifier(increase_damage) << " "
 				 << _n("damage","damage", inc_damage);
 		}
 
 		if(increase_attacks.empty() == false) {
 			int inc_attacks = lexical_cast<int>(increase_attacks);
-			desc << utils::signed_value(inc_attacks) << " "
+			desc << utils::print_modifier(increase_attacks) << " "
 				 << _n("strike", "strikes", inc_attacks);
 		}