diff --git a/calc_gate.c b/calc_gate.c
index 743b50e..066e62a 100644
--- a/calc_gate.c
+++ b/calc_gate.c
@@ -95,7 +95,7 @@ int data_validity_check(struct param_gate *param)
 	if(param->water_depth_behind_of_gate <-0.0000001){
 		return -1;
 	}
-	if(param->gate_width <0.0000001){
+	if(param->gate_width <-0.0000001){
 		return -1;
 	}
 	return 0;