diff --git a/src/units/frame.cpp b/src/units/frame.cpp
index 51e1491e58c9..91e56bb83142 100644
--- a/src/units/frame.cpp
+++ b/src/units/frame.cpp
@@ -888,7 +888,7 @@ const frame_parameters unit_frame::merge_parameters(int current_time, const fram
 	/** The engine provides a highlight ratio for selected units and visible "invisible" units */
 	result.highlight_ratio = current_val.highlight_ratio != 1.0 ? current_val.highlight_ratio : animation_val.highlight_ratio;
 	if(primary && engine_val.highlight_ratio != 1.0) {
-		result.highlight_ratio = result.highlight_ratio + engine_val.highlight_ratio - 1.0; // selected unit
+		result.highlight_ratio = result.highlight_ratio * engine_val.highlight_ratio; // selected unit
 	}
 
 	assert(engine_val.offset == 0);