diff --git a/server/gameserver/collision.cc b/server/gameserver/collision.cc
index 7e9c49bb..7ba718cf 100644
--- a/server/gameserver/collision.cc
+++ b/server/gameserver/collision.cc
@@ -144,11 +144,10 @@ bool Collision::Check2dRotationRectangle(float rx, float ry, float r, float dx,
     return (tmp_dx1 - new_rx) * (tmp_dx1 - new_rx) + (tmp_dy1 - new_ry) * (tmp_dy1 - new_ry) <= r * r;
 }
 
-bool Collision::IsNearInRange(const glm::vec3& center, const glm::vec3& pos, float range)
+bool Collision::InSquare(const glm::vec3& center, const glm::vec3& pos, float side_len)
 {
-
-}
-
-bool Collision::IsNearOutRange(const glm::vec3& center, const glm::vec3& pos, float range) {
-
+    float x_distance = std::fabs(pos.x - center.x);
+    float z_distance = std::fabs(pos.z - center.z);
+    return (x_distance < side_len &&
+            z_distance < side_len);
 }
diff --git a/server/gameserver/collision.h b/server/gameserver/collision.h
index 4b27050b..d97e0f69 100644
--- a/server/gameserver/collision.h
+++ b/server/gameserver/collision.h
@@ -24,7 +24,6 @@ class Collision
     */
     static bool Check2dRotationRectangle(float rx, float ry, float r, float dx, float dy, float dw, float dh, float dro);
 
-    static bool IsNearInRange(const glm::vec3& center, const glm::vec3& pos, float range);
-    static bool IsNearOutRange(const glm::vec3& center, const glm::vec3& pos, float range);
+    static bool InSquare(const glm::vec3& center, const glm::vec3& pos, float side_len);
 
 };
diff --git a/server/gameserver/new_hero_agent.cc b/server/gameserver/new_hero_agent.cc
index a430534b..0d40311a 100644
--- a/server/gameserver/new_hero_agent.cc
+++ b/server/gameserver/new_hero_agent.cc
@@ -248,7 +248,7 @@ bool HeroAgent::HasBuffEffect(int effect_id)
 
 bool HeroAgent::IsNearGas(float range)
 {
-    return Collision::IsNearInRange
+    return Collision::InSquare
         (owner_->GetPos().ToGlmVec3(),
          owner_->GetPos().ToGlmVec3(),
          range);
@@ -260,7 +260,7 @@ bool HeroAgent::MasterInRange(float range)
         !owner_->AsHero()->master.Get()) {
         return false;
     }
-    return Collision::IsNearInRange
+    return Collision::InSquare
         (owner_->AsHero()->master.Get()->GetPos().ToGlmVec3(),
          owner_->GetPos().ToGlmVec3(),
          range);