diff --git a/zone/position.cpp b/zone/position.cpp
index a5f0cf5f1..d7e0d48f4 100644
--- a/zone/position.cpp
+++ b/zone/position.cpp
@@ -63,15 +63,15 @@ xyz_heading::operator xy_location() const {
     return xy_location(m_X,m_Y);
 }
 
-const xyz_heading xyz_heading::operator +(const xyz_location& rhs) {
+const xyz_heading xyz_heading::operator +(const xyz_location& rhs) const{
     return xyz_heading(m_X + rhs.m_X, m_Y + rhs.m_Y, m_Z + rhs.m_Z, m_Heading);
 }
 
-const xyz_heading xyz_heading::operator +(const xy_location& rhs) {
+const xyz_heading xyz_heading::operator +(const xy_location& rhs) const{
     return xyz_heading(m_X + rhs.m_X, m_Y + rhs.m_Y, m_Z, m_Heading);
 }
 
-const xyz_heading xyz_heading::operator -(const xyz_location& rhs) {
+const xyz_heading xyz_heading::operator -(const xyz_location& rhs) const{
     return xyz_heading(m_X - rhs.m_X, m_Y - rhs.m_Y, m_Z - rhs.m_Z, m_Heading);
 }
 
@@ -92,7 +92,7 @@ xyz_location::operator xy_location() const {
     return xy_location(m_X, m_Y);
 }
 
-const xyz_location xyz_location::operator -(const xyz_location& rhs) {
+const xyz_location xyz_location::operator -(const xyz_location& rhs) const {
     return xyz_location(m_X - rhs.m_X, m_Y - rhs.m_Y, m_Z - rhs.m_Z);
 }
 
diff --git a/zone/position.h b/zone/position.h
index 900d2cdfe..eadd187ce 100644
--- a/zone/position.h
+++ b/zone/position.h
@@ -43,7 +43,7 @@ public:
 
     operator xy_location() const;
 
-    const xyz_location operator -(const xyz_location& rhs);
+    const xyz_location operator -(const xyz_location& rhs) const;
 
     void ABS_XYZ();
     bool isOrigin() const { return m_X == 0 && m_Y == 0 && m_Z == 0;}
@@ -70,10 +70,10 @@ public:
     operator xyz_location() const;
     operator xy_location() const;
 
-    const xyz_heading operator +(const xyz_location& rhs);
-    const xyz_heading operator +(const xy_location& rhs);
+    const xyz_heading operator +(const xyz_location& rhs) const;
+    const xyz_heading operator +(const xy_location& rhs) const;
 
-    const xyz_heading operator -(const xyz_location& rhs);
+    const xyz_heading operator -(const xyz_location& rhs) const;
 
     bool isOrigin() const { return m_X == 0.0f && m_Y == 0.0f && m_Z == 0.0f;}
 };