diff --git a/core/src/com/unciv/models/ruleset/tile/TileImprovement.kt b/core/src/com/unciv/models/ruleset/tile/TileImprovement.kt
index cb0bee157d..c97b8e3b17 100644
--- a/core/src/com/unciv/models/ruleset/tile/TileImprovement.kt
+++ b/core/src/com/unciv/models/ruleset/tile/TileImprovement.kt
@@ -26,7 +26,7 @@ class TileImprovement : NamedStats(), ICivilopediaText {
     fun getTurnsToBuild(civInfo: CivilizationInfo): Int {
         var realTurnsToBuild = turnsToBuild.toFloat() * civInfo.gameInfo.gameParameters.gameSpeed.modifier
         for (unique in civInfo.getMatchingUniques("[]% tile improvement construction time")) {
-            realTurnsToBuild *= 1 - unique.params[0].toFloat() / 100f
+            realTurnsToBuild *= 1 + unique.params[0].toFloat() / 100f
         }
         // Deprecated since 3.14.17
             if (civInfo.hasUnique("Worker construction increased 25%"))