diff --git a/src/handler/server/ReadCoils.js b/src/handler/server/ReadCoils.js
index e2e16fd..6726bd6 100644
--- a/src/handler/server/ReadCoils.js
+++ b/src/handler/server/ReadCoils.js
@@ -19,7 +19,7 @@ module.exports = stampit()
         this.log.debug('handling read coils request.')
 
         if (pdu.length !== 5) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x81, 0)
           buf.writeUInt8(0x02, 1)
@@ -35,7 +35,7 @@ module.exports = stampit()
         var mem = this.getCoils()
 
         if (start > mem.length * 8 || start + quantity > mem.length * 8) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
           buf.writeUInt8(0x81, 0)
           buf.writeUInt8(0x02, 1)
           cb(buf)
diff --git a/src/handler/server/ReadDiscreteInputs.js b/src/handler/server/ReadDiscreteInputs.js
index 1634def..7d1c35f 100644
--- a/src/handler/server/ReadDiscreteInputs.js
+++ b/src/handler/server/ReadDiscreteInputs.js
@@ -21,7 +21,7 @@ var handler = stampit()
         if (pdu.length !== 5) {
           this.log.debug('wrong pdu length.')
 
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x82, 0)
           buf.writeUInt8(0x02, 1)
@@ -40,7 +40,7 @@ var handler = stampit()
         if (start > mem.length * 8 || start + quantity > mem.length * 8) {
           this.log.debug('wrong pdu length.')
 
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x82, 0)
           buf.writeUInt8(0x02, 1)
diff --git a/src/handler/server/ReadHoldingRegisters.js b/src/handler/server/ReadHoldingRegisters.js
index 7f6485c..c2543f1 100644
--- a/src/handler/server/ReadHoldingRegisters.js
+++ b/src/handler/server/ReadHoldingRegisters.js
@@ -21,7 +21,7 @@ module.exports = stampit()
         if (pdu.length !== 5) {
           this.log.debug('wrong pdu length.')
 
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x83, 0)
           buf.writeUInt8(0x02, 1)
@@ -40,7 +40,7 @@ module.exports = stampit()
 
         if (byteStart > mem.length || byteStart + (quantity * 2) > mem.length) {
           this.log.debug('request outside register boundaries.')
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x83, 0)
           buf.writeUInt8(0x02, 1)
diff --git a/src/handler/server/ReadInputRegisters.js b/src/handler/server/ReadInputRegisters.js
index 52f22c2..cb58b75 100644
--- a/src/handler/server/ReadInputRegisters.js
+++ b/src/handler/server/ReadInputRegisters.js
@@ -19,7 +19,7 @@ module.exports = stampit()
         this.log.debug('handling read input registers request.')
 
         if (pdu.length !== 5) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x84, 0)
           buf.writeUInt8(0x02, 1)
@@ -36,7 +36,7 @@ module.exports = stampit()
         var mem = this.getInput()
 
         if (byteStart > mem.length || byteStart + (quantity * 2) > mem.length) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x84, 0)
           buf.writeUInt8(0x02, 1)
diff --git a/src/handler/server/WriteMultipleCoils.js b/src/handler/server/WriteMultipleCoils.js
index 9c0e369..eb5b665 100644
--- a/src/handler/server/WriteMultipleCoils.js
+++ b/src/handler/server/WriteMultipleCoils.js
@@ -19,7 +19,7 @@ module.exports = stampit()
         this.log.debug('handling write multiple coils request.')
 
         if (pdu.length < 3) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x8F, 0)
           buf.writeUInt8(0x02, 1)
@@ -37,7 +37,7 @@ module.exports = stampit()
 
         // error response
         if (start > mem.length * 8 || start + quantity > mem.length * 8) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x8F, 0)
           buf.writeUInt8(0x02, 1)
diff --git a/src/handler/server/WriteMultipleRegisters.js b/src/handler/server/WriteMultipleRegisters.js
index a274292..039de34 100644
--- a/src/handler/server/WriteMultipleRegisters.js
+++ b/src/handler/server/WriteMultipleRegisters.js
@@ -19,7 +19,7 @@ module.exports = stampit()
         this.log.debug('handling write multiple registers request.')
 
         if (pdu.length < 3) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x90, 0)
           buf.writeUInt8(0x02, 1)
@@ -33,7 +33,7 @@ module.exports = stampit()
         var byteCount = pdu.readUInt8(5)
 
         if (quantity > 0x007b) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x90, 0)
           buf.writeUInt8(0x03, 1)
diff --git a/src/handler/server/WriteSingleCoil.js b/src/handler/server/WriteSingleCoil.js
index 68a42b3..9171579 100644
--- a/src/handler/server/WriteSingleCoil.js
+++ b/src/handler/server/WriteSingleCoil.js
@@ -19,7 +19,7 @@ module.exports = stampit()
         this.log.debug('handling write single coil request.')
 
         if (pdu.length !== 5) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x85, 0)
           buf.writeUInt8(0x02, 1)
@@ -31,7 +31,7 @@ module.exports = stampit()
         var value = !(pdu.readUInt16BE(3) === 0x0000)
 
         if (pdu.readUInt16BE(3) !== 0x0000 && pdu.readUInt16BE(3) !== 0xFF00) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x85, 0)
           buf.writeUInt8(0x03, 1)
diff --git a/src/handler/server/WriteSingleRegister.js b/src/handler/server/WriteSingleRegister.js
index 00697b0..1f8e687 100644
--- a/src/handler/server/WriteSingleRegister.js
+++ b/src/handler/server/WriteSingleRegister.js
@@ -19,7 +19,7 @@ module.exports = stampit()
         this.log.debug('handling write single register request.')
 
         if (pdu.length !== 5) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x86, 0)
           buf.writeUInt8(0x02, 1)
@@ -36,7 +36,7 @@ module.exports = stampit()
         var mem = this.getHolding()
 
         if (byteAddress > mem.length) {
-          var buf = Buffer.allocUnsafe(2)
+          let buf = Buffer.allocUnsafe(2)
 
           buf.writeUInt8(0x86, 0)
           buf.writeUInt8(0x02, 1)