diff --git a/build.go b/build.go
index 79569353..acb16fee 100644
--- a/build.go
+++ b/build.go
@@ -301,6 +301,7 @@ func runCommand(cmd string, target target) {
 			ok = gometalinter("ineffassign", dirs) && ok
 			ok = gometalinter("unused", dirs) && ok
 			ok = gometalinter("staticcheck", dirs) && ok
+			ok = gometalinter("unconvert", dirs) && ok
 			if !ok {
 				os.Exit(1)
 			}
@@ -366,6 +367,7 @@ func setup() {
 		"github.com/FiloSottile/gvt",
 		"github.com/golang/lint/golint",
 		"github.com/gordonklaus/ineffassign",
+		"github.com/mdempsky/unconvert",
 		"github.com/mitchellh/go-wordwrap",
 		"github.com/opennota/check/cmd/...",
 		"github.com/tsenart/deadcode",
diff --git a/cmd/stcli/utils.go b/cmd/stcli/utils.go
index d6cae2b3..f9c3fbb1 100644
--- a/cmd/stcli/utils.go
+++ b/cmd/stcli/utils.go
@@ -140,7 +140,7 @@ func parsePort(input string) int {
 	if port < 1 || port > 65535 {
 		die(input + " is not a valid port\nExpected value between 1 and 65535")
 	}
-	return int(port)
+	return port
 }
 
 func validAddress(input string) {
diff --git a/cmd/stgenfiles/main.go b/cmd/stgenfiles/main.go
index 3ce491a0..5e89150f 100644
--- a/cmd/stgenfiles/main.go
+++ b/cmd/stgenfiles/main.go
@@ -66,7 +66,7 @@ func generateFiles(dir string, files, maxexp int, srcname string) error {
 }
 
 func generateOneFile(fd io.ReadSeeker, p1 string, s int64) error {
-	src := io.LimitReader(&inifiteReader{fd}, int64(s))
+	src := io.LimitReader(&inifiteReader{fd}, s)
 	dst, err := os.Create(p1)
 	if err != nil {
 		return err
diff --git a/cmd/strelaypoolsrv/main.go b/cmd/strelaypoolsrv/main.go
index 16356f07..9f349822 100644
--- a/cmd/strelaypoolsrv/main.go
+++ b/cmd/strelaypoolsrv/main.go
@@ -249,13 +249,13 @@ func handleRequest(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Access-Control-Allow-Origin", "*")
 	switch r.Method {
 	case "GET":
-		if limit(r.RemoteAddr, getLRUCache, getMut, getLimit, int64(getLimitBurst)) {
+		if limit(r.RemoteAddr, getLRUCache, getMut, getLimit, getLimitBurst) {
 			w.WriteHeader(429)
 			return
 		}
 		handleGetRequest(w, r)
 	case "POST":
-		if limit(r.RemoteAddr, postLRUCache, postMut, postLimit, int64(postLimitBurst)) {
+		if limit(r.RemoteAddr, postLRUCache, postMut, postLimit, postLimitBurst) {
 			w.WriteHeader(429)
 			return
 		}
diff --git a/cmd/strelaysrv/session.go b/cmd/strelaysrv/session.go
index 671335ce..7a54d14d 100644
--- a/cmd/strelaysrv/session.go
+++ b/cmd/strelaysrv/session.go
@@ -216,7 +216,7 @@ done:
 func (s *session) GetClientInvitationMessage() protocol.SessionInvitation {
 	return protocol.SessionInvitation{
 		From:         s.serverid[:],
-		Key:          []byte(s.clientkey),
+		Key:          s.clientkey,
 		Address:      sessionAddress,
 		Port:         sessionPort,
 		ServerSocket: false,
@@ -226,7 +226,7 @@ func (s *session) GetClientInvitationMessage() protocol.SessionInvitation {
 func (s *session) GetServerInvitationMessage() protocol.SessionInvitation {
 	return protocol.SessionInvitation{
 		From:         s.clientid[:],
-		Key:          []byte(s.serverkey),
+		Key:          s.serverkey,
 		Address:      sessionAddress,
 		Port:         sessionPort,
 		ServerSocket: true,
diff --git a/cmd/syncthing/main.go b/cmd/syncthing/main.go
index b1bf33af..12eef8d1 100644
--- a/cmd/syncthing/main.go
+++ b/cmd/syncthing/main.go
@@ -1070,7 +1070,7 @@ func getFreePort(host string, ports ...int) (int, error) {
 }
 
 func standbyMonitor() {
-	restartDelay := time.Duration(60 * time.Second)
+	restartDelay := 60 * time.Second
 	now := time.Now()
 	for {
 		time.Sleep(10 * time.Second)
diff --git a/lib/db/blockmap.go b/lib/db/blockmap.go
index 57c3fb11..758c51c8 100644
--- a/lib/db/blockmap.go
+++ b/lib/db/blockmap.go
@@ -209,7 +209,7 @@ func blockKeyInto(o, hash []byte, folder uint32, file string) []byte {
 	}
 	o[0] = KeyTypeBlock
 	binary.BigEndian.PutUint32(o[keyPrefixLen:], folder)
-	copy(o[keyPrefixLen+keyFolderLen:], []byte(hash))
+	copy(o[keyPrefixLen+keyFolderLen:], hash)
 	copy(o[keyPrefixLen+keyFolderLen+keyHashLen:], []byte(file))
 	return o
 }
diff --git a/lib/db/leveldb_dbinstance.go b/lib/db/leveldb_dbinstance.go
index dfa2630a..e16ee033 100644
--- a/lib/db/leveldb_dbinstance.go
+++ b/lib/db/leveldb_dbinstance.go
@@ -635,7 +635,7 @@ func (db *Instance) deviceKeyInto(k []byte, folder, device, file []byte) []byte
 	k[0] = KeyTypeDevice
 	binary.BigEndian.PutUint32(k[keyPrefixLen:], db.folderIdx.ID(folder))
 	binary.BigEndian.PutUint32(k[keyPrefixLen+keyFolderLen:], db.deviceIdx.ID(device))
-	copy(k[keyPrefixLen+keyFolderLen+keyDeviceLen:], []byte(file))
+	copy(k[keyPrefixLen+keyFolderLen+keyDeviceLen:], file)
 	return k[:reqLen]
 }
 
@@ -670,7 +670,7 @@ func (db *Instance) globalKey(folder, file []byte) []byte {
 	k := make([]byte, keyPrefixLen+keyFolderLen+len(file))
 	k[0] = KeyTypeGlobal
 	binary.BigEndian.PutUint32(k[keyPrefixLen:], db.folderIdx.ID(folder))
-	copy(k[keyPrefixLen+keyFolderLen:], []byte(file))
+	copy(k[keyPrefixLen+keyFolderLen:], file)
 	return k
 }
 
diff --git a/lib/protocol/protocol.go b/lib/protocol/protocol.go
index bb5c6d84..b955e79d 100644
--- a/lib/protocol/protocol.go
+++ b/lib/protocol/protocol.go
@@ -522,7 +522,7 @@ func (c *rawConnection) handleRequest(req Request) {
 		buf = make([]byte, size)
 	}
 
-	err := c.receiver.Request(c.id, req.Folder, req.Name, int64(req.Offset), req.Hash, req.FromTemporary, buf)
+	err := c.receiver.Request(c.id, req.Folder, req.Name, req.Offset, req.Hash, req.FromTemporary, buf)
 	if err != nil {
 		c.send(&Response{
 			ID:   req.ID,
diff --git a/lib/scanner/blocks.go b/lib/scanner/blocks.go
index eb5ad2bc..89a5da63 100644
--- a/lib/scanner/blocks.go
+++ b/lib/scanner/blocks.go
@@ -56,7 +56,7 @@ func Blocks(r io.Reader, blocksize int, sizehint int64, counter Counter) ([]prot
 		}
 
 		if counter != nil {
-			counter.Update(int64(n))
+			counter.Update(n)
 		}
 
 		// Carve out a hash-sized chunk of "hashes" to store the hash for this
@@ -72,7 +72,7 @@ func Blocks(r io.Reader, blocksize int, sizehint int64, counter Counter) ([]prot
 		}
 
 		blocks = append(blocks, b)
-		offset += int64(n)
+		offset += n
 
 		hf.Reset()
 		whf.Reset()
diff --git a/lib/scanner/walk.go b/lib/scanner/walk.go
index 7784a859..c296c362 100644
--- a/lib/scanner/walk.go
+++ b/lib/scanner/walk.go
@@ -163,7 +163,7 @@ func (w *walker) walk() (chan protocol.FileInfo, error) {
 
 		for file := range toHashChan {
 			filesToHash = append(filesToHash, file)
-			total += int64(file.Size)
+			total += file.Size
 		}
 
 		realToHashChan := make(chan protocol.FileInfo)
diff --git a/lib/sync/debug.go b/lib/sync/debug.go
index e0618269..ea2ffdc9 100644
--- a/lib/sync/debug.go
+++ b/lib/sync/debug.go
@@ -17,7 +17,7 @@ import (
 )
 
 var (
-	threshold = time.Duration(100 * time.Millisecond)
+	threshold = 100 * time.Millisecond
 	l         = logger.DefaultLogger.NewFacility("sync", "Mutexes")
 
 	// We make an exception in this package and have an actual "if debug { ...