diff --git a/netNav/netNav.lua b/netNav/netNav.lua
index d58d5ee..53914d7 100644
--- a/netNav/netNav.lua
+++ b/netNav/netNav.lua
@@ -162,7 +162,7 @@ local function detectAll(currPos)
 end
 
 local function findSensor()
-	for _, side in ipairs(peripheral.getNames()) do
+	for _, side in ipairs({"left", "right"}) do
 		if peripheral.getType(side) == "turtlesensorenvironment" then
 			return side
 		end
@@ -247,6 +247,18 @@ local function _goto(x, y, z, maxDistance)
 		if not position then
 			return false, "couldn't determine location"
 		end
+	else
+		-- check if position has changed
+		local curPos = {gps.locate()}
+		if #curPos == 3 then
+			curPos = vector.new(unpack(curPos))
+			if not aStar.vectorEquals(curPos, position) then -- position has changed
+				position = findPosition()
+				if not position then
+					return false, "couldn't determine location"
+				end
+			end
+		end
 	end
 	
 	local goal = vector.new(tonumber(x), tonumber(y), tonumber(z))
diff --git a/starNav/starNav.lua b/starNav/starNav.lua
index 9618b99..edf2bba 100644
--- a/starNav/starNav.lua
+++ b/starNav/starNav.lua
@@ -157,7 +157,7 @@ local function detectAll(currPos)
 end
 
 local function findSensor()
-	for _, side in ipairs(peripheral.getNames()) do
+	for _, side in ipairs({"left", "right"}) do
 		if peripheral.getType(side) == "turtlesensorenvironment" then
 			return side
 		end
@@ -241,6 +241,18 @@ local function _goto(x, y, z, maxDistance)
 		if not position then
 			return false, "couldn't determine location"
 		end
+	else
+		-- check if position has changed
+		local curPos = {gps.locate()}
+		if #curPos == 3 then
+			curPos = vector.new(unpack(curPos))
+			if not aStar.vectorEquals(curPos, position) then -- position has changed
+				position = findPosition()
+				if not position then
+					return false, "couldn't determine location"
+				end
+			end
+		end
 	end
 	
 	local goal = vector.new(tonumber(x), tonumber(y), tonumber(z))