diff --git a/cmd/gateway/hdfs/gateway-hdfs.go b/cmd/gateway/hdfs/gateway-hdfs.go
index 0f190a7aa..c47dc990c 100644
--- a/cmd/gateway/hdfs/gateway-hdfs.go
+++ b/cmd/gateway/hdfs/gateway-hdfs.go
@@ -18,6 +18,7 @@ package hdfs
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -280,7 +281,7 @@ func hdfsToObjectErr(ctx context.Context, err error, params ...string) error {
 			return minio.PrefixAccessDenied{Bucket: bucket, Object: object}
 		}
 		return minio.BucketAlreadyOwnedByYou{Bucket: bucket}
-	case isSysErrNotEmpty(err):
+	case errors.Is(err, syscall.ENOTEMPTY):
 		if object != "" {
 			return minio.PrefixAccessDenied{Bucket: bucket, Object: object}
 		}
@@ -387,20 +388,6 @@ func (n *hdfsObjects) ListObjects(ctx context.Context, bucket, prefix, marker, d
 	return minio.ListObjects(ctx, n, bucket, prefix, marker, delimiter, maxKeys, n.listPool, n.listDirFactory(), getObjectInfo, getObjectInfo)
 }
 
-// Check if the given error corresponds to ENOTEMPTY for unix
-// and ERROR_DIR_NOT_EMPTY for windows (directory not empty).
-func isSysErrNotEmpty(err error) bool {
-	if err == syscall.ENOTEMPTY {
-		return true
-	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		if pathErr.Err == syscall.ENOTEMPTY {
-			return true
-		}
-	}
-	return false
-}
-
 // deleteObject deletes a file path if its empty. If it's successfully deleted,
 // it will recursively move up the tree, deleting empty parent directories
 // until it finds one with files in it. Returns nil for a non-empty directory.
@@ -411,16 +398,13 @@ func (n *hdfsObjects) deleteObject(basePath, deletePath string) error {
 
 	// Attempt to remove path.
 	if err := n.clnt.Remove(deletePath); err != nil {
-		switch {
-		case err == syscall.ENOTEMPTY:
-		case isSysErrNotEmpty(err):
+		if errors.Is(err, syscall.ENOTEMPTY) {
 			// Ignore errors if the directory is not empty. The server relies on
 			// this functionality, and sometimes uses recursion that should not
 			// error on parent directories.
 			return nil
-		default:
-			return err
 		}
+		return err
 	}
 
 	// Trailing slash is removed when found to ensure
diff --git a/cmd/http-tracer.go b/cmd/http-tracer.go
index b0a33e007..ef9b89f9f 100644
--- a/cmd/http-tracer.go
+++ b/cmd/http-tracer.go
@@ -175,7 +175,7 @@ func Trace(f http.HandlerFunc, logBody bool, w http.ResponseWriter, r *http.Requ
 	name := getOpName(runtime.FuncForPC(reflect.ValueOf(f).Pointer()).Name())
 
 	// Setup a http request body recorder
-	reqHeaders := cloneHeader(r.Header)
+	reqHeaders := r.Header.Clone()
 	reqHeaders.Set("Content-Length", strconv.Itoa(int(r.ContentLength)))
 	reqHeaders.Set("Host", r.Host)
 	for _, enc := range r.TransferEncoding {
@@ -211,7 +211,7 @@ func Trace(f http.HandlerFunc, logBody bool, w http.ResponseWriter, r *http.Requ
 
 	rs := trace.ResponseInfo{
 		Time:       time.Now().UTC(),
-		Headers:    cloneHeader(respBodyRecorder.Header()),
+		Headers:    respBodyRecorder.Header().Clone(),
 		StatusCode: respBodyRecorder.statusCode,
 		Body:       respBodyRecorder.Body(),
 	}
diff --git a/cmd/posix-errors.go b/cmd/posix-errors.go
index 7fea4061c..e68cf8bb8 100644
--- a/cmd/posix-errors.go
+++ b/cmd/posix-errors.go
@@ -17,6 +17,7 @@
 package cmd
 
 import (
+	"errors"
 	"os"
 	"runtime"
 	"syscall"
@@ -24,86 +25,54 @@ import (
 
 // Function not implemented error
 func isSysErrNoSys(err error) bool {
-	if err == syscall.ENOSYS {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.ENOSYS
-
+	return errors.Is(err, syscall.ENOSYS)
 }
 
 // Not supported error
 func isSysErrOpNotSupported(err error) bool {
-	if err == syscall.EOPNOTSUPP {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.EOPNOTSUPP
-
+	return errors.Is(err, syscall.EOPNOTSUPP)
 }
 
 // No space left on device error
 func isSysErrNoSpace(err error) bool {
-	if err == syscall.ENOSPC {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.ENOSPC
+	return errors.Is(err, syscall.ENOSPC)
 }
 
 // Input/output error
 func isSysErrIO(err error) bool {
-	if err == syscall.EIO {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.EIO
+	return errors.Is(err, syscall.EIO)
 }
 
 // Check if the given error corresponds to EISDIR (is a directory).
 func isSysErrIsDir(err error) bool {
-	if err == syscall.EISDIR {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.EISDIR
-
+	return errors.Is(err, syscall.EISDIR)
 }
 
 // Check if the given error corresponds to ENOTDIR (is not a directory).
 func isSysErrNotDir(err error) bool {
-	if err == syscall.ENOTDIR {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.ENOTDIR
+	return errors.Is(err, syscall.ENOTDIR)
 }
 
 // Check if the given error corresponds to the ENAMETOOLONG (name too long).
 func isSysErrTooLong(err error) bool {
-	if err == syscall.ENAMETOOLONG {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && pathErr.Err == syscall.ENAMETOOLONG
+	return errors.Is(err, syscall.ENAMETOOLONG)
 }
 
 // Check if the given error corresponds to ENOTEMPTY for unix
 // and ERROR_DIR_NOT_EMPTY for windows (directory not empty).
 func isSysErrNotEmpty(err error) bool {
-	if err == syscall.ENOTEMPTY {
+	if errors.Is(err, syscall.ENOTEMPTY) {
 		return true
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
+	var pathErr *os.PathError
+	if errors.As(err, &pathErr) {
 		if runtime.GOOS == globalWindowsOSName {
-			if errno, _ok := pathErr.Err.(syscall.Errno); _ok && errno == 0x91 {
+			var errno syscall.Errno
+			if errors.As(pathErr.Err, &errno) {
 				// ERROR_DIR_NOT_EMPTY
-				return true
+				return errno == 0x91
 			}
 		}
-		if pathErr.Err == syscall.ENOTEMPTY {
-			return true
-		}
 	}
 	return false
 }
@@ -113,10 +82,12 @@ func isSysErrPathNotFound(err error) bool {
 	if runtime.GOOS != globalWindowsOSName {
 		return false
 	}
-	if pathErr, ok := err.(*os.PathError); ok {
-		if errno, _ok := pathErr.Err.(syscall.Errno); _ok && errno == 0x03 {
+	var pathErr *os.PathError
+	if errors.As(err, &pathErr) {
+		var errno syscall.Errno
+		if errors.As(pathErr.Err, &errno) {
 			// ERROR_PATH_NOT_FOUND
-			return true
+			return errno == 0x03
 		}
 	}
 	return false
@@ -128,20 +99,22 @@ func isSysErrHandleInvalid(err error) bool {
 		return false
 	}
 	// Check if err contains ERROR_INVALID_HANDLE errno
-	errno, ok := err.(syscall.Errno)
-	return ok && errno == 0x6
+	var pathErr *os.PathError
+	if errors.As(err, &pathErr) {
+		var errno syscall.Errno
+		if errors.As(pathErr.Err, &errno) {
+			// ERROR_PATH_NOT_FOUND
+			return errno == 0x6
+		}
+	}
+	return false
 }
 
 func isSysErrCrossDevice(err error) bool {
-	e, ok := err.(*os.LinkError)
-	return ok && e.Err == syscall.EXDEV
+	return errors.Is(err, syscall.EXDEV)
 }
 
 // Check if given error corresponds to too many open files
 func isSysErrTooManyFiles(err error) bool {
-	if err == syscall.ENFILE || err == syscall.EMFILE {
-		return true
-	}
-	pathErr, ok := err.(*os.PathError)
-	return ok && (pathErr.Err == syscall.ENFILE || pathErr.Err == syscall.EMFILE)
+	return errors.Is(err, syscall.ENFILE) || errors.Is(err, syscall.EMFILE)
 }
diff --git a/cmd/posix.go b/cmd/posix.go
index dc04d9080..876cd024c 100644
--- a/cmd/posix.go
+++ b/cmd/posix.go
@@ -19,6 +19,7 @@ package cmd
 import (
 	"context"
 	"encoding/hex"
+	"errors"
 	"io"
 	"io/ioutil"
 	"os"
@@ -845,17 +846,11 @@ func (s *posix) ReadAll(volume, path string) (buf []byte, err error) {
 			return nil, errFileNotFound
 		} else if os.IsPermission(err) {
 			return nil, errFileAccessDenied
-		} else if pathErr, ok := err.(*os.PathError); ok {
-			switch pathErr.Err {
-			case syscall.ENOTDIR, syscall.EISDIR:
-				return nil, errFileNotFound
-			default:
-				if isSysErrHandleInvalid(pathErr.Err) {
-					// This case is special and needs to be handled for windows.
-					return nil, errFileNotFound
-				}
-			}
-			return nil, pathErr
+		} else if errors.Is(err, syscall.ENOTDIR) || errors.Is(err, syscall.EISDIR) {
+			return nil, errFileNotFound
+		} else if isSysErrHandleInvalid(err) {
+			// This case is special and needs to be handled for windows.
+			return nil, errFileNotFound
 		} else if isSysErrIO(err) {
 			return nil, errFaultyDisk
 		}
diff --git a/cmd/ui-errors-utils.go b/cmd/ui-errors-utils.go
index aea5c5779..a5eeab94b 100644
--- a/cmd/ui-errors-utils.go
+++ b/cmd/ui-errors-utils.go
@@ -17,9 +17,9 @@
 package cmd
 
 import (
+	"errors"
 	"fmt"
 	"io"
-	"net"
 	"os"
 	"syscall"
 )
@@ -80,27 +80,15 @@ func errorToUIErr(err error) uiErr {
 	}
 
 	// Show a generic message for known golang errors
-	switch e := err.(type) {
-	case *net.OpError:
-		if e.Op == "listen" {
-			if oe, ok := e.Err.(*os.SyscallError); ok {
-				if oe.Err == syscall.EADDRINUSE {
-					return uiErrPortAlreadyInUse(e).Msg("Specified port '" + e.Addr.String() + "' is already in use")
-				} else if oe.Err == syscall.EACCES {
-					return uiErrPortAccess(e).Msg("Insufficient permissions to use specified port '" + e.Addr.String() + "'")
-				}
-			}
-		}
-	case *os.PathError:
-		if os.IsPermission(e) {
-			return uiErrNoPermissionsToAccessDirFiles(e).Msg("Insufficient permissions to access path, `" + e.Path + "`")
-		}
-	}
-
-	switch err {
-	case io.ErrUnexpectedEOF:
+	if errors.Is(err, syscall.EADDRINUSE) {
+		return uiErrPortAlreadyInUse(err).Msg("Specified port is already in use")
+	} else if errors.Is(err, syscall.EACCES) {
+		return uiErrPortAccess(err).Msg("Insufficient permissions to use specified port")
+	} else if os.IsPermission(err) {
+		return uiErrNoPermissionsToAccessDirFiles(err).Msg("Insufficient permissions to access path")
+	} else if errors.Is(err, io.ErrUnexpectedEOF) {
 		return uiErrUnexpectedDataContent(err)
-	default:
+	} else {
 		// Failed to identify what type of error this, return a simple UI error
 		return uiErr{msg: err.Error()}
 	}
diff --git a/cmd/utils.go b/cmd/utils.go
index 207e20822..052d743dc 100644
--- a/cmd/utils.go
+++ b/cmd/utils.go
@@ -53,25 +53,13 @@ func IsErrIgnored(err error, ignoredErrs ...error) bool {
 // IsErr returns whether given error is exact error.
 func IsErr(err error, errs ...error) bool {
 	for _, exactErr := range errs {
-		if err == exactErr {
+		if errors.Is(err, exactErr) {
 			return true
 		}
 	}
 	return false
 }
 
-// make a copy of http.Header
-func cloneHeader(h http.Header) http.Header {
-	h2 := make(http.Header, len(h))
-	for k, vv := range h {
-		vv2 := make([]string, len(vv))
-		copy(vv2, vv)
-		h2[k] = vv2
-
-	}
-	return h2
-}
-
 func request2BucketObjectName(r *http.Request) (bucketName, objectName string) {
 	path, err := getResource(r.URL.Path, r.Host, globalDomainNames)
 	if err != nil {
@@ -289,7 +277,7 @@ var globalProfiler minioProfiler
 
 // dump the request into a string in JSON format.
 func dumpRequest(r *http.Request) string {
-	header := cloneHeader(r.Header)
+	header := r.Header.Clone()
 	header.Set("Host", r.Host)
 	// Replace all '%' to '%%' so that printer format parser
 	// to ignore URL encoded values.
diff --git a/cmd/utils_test.go b/cmd/utils_test.go
index e5d2a13cd..195e31bad 100644
--- a/cmd/utils_test.go
+++ b/cmd/utils_test.go
@@ -30,30 +30,6 @@ import (
 	"testing"
 )
 
-// Tests http.Header clone.
-func TestCloneHeader(t *testing.T) {
-	headers := []http.Header{
-		{
-			"Content-Type":   {"text/html; charset=UTF-8"},
-			"Content-Length": {"0"},
-		},
-		{
-			"Content-Length": {"0", "1", "2"},
-		},
-		{
-			"Expires":          {"-1"},
-			"Content-Length":   {"0"},
-			"Content-Encoding": {"gzip"},
-		},
-	}
-	for i, header := range headers {
-		clonedHeader := cloneHeader(header)
-		if !reflect.DeepEqual(header, clonedHeader) {
-			t.Errorf("Test %d failed", i+1)
-		}
-	}
-}
-
 // Tests maximum object size.
 func TestMaxObjectSize(t *testing.T) {
 	sizes := []struct {
diff --git a/pkg/lock/lock_nix.go b/pkg/lock/lock_nix.go
index 3fd581fca..c7c3a1a32 100644
--- a/pkg/lock/lock_nix.go
+++ b/pkg/lock/lock_nix.go
@@ -19,7 +19,6 @@
 package lock
 
 import (
-	"fmt"
 	"os"
 	"syscall"
 )
@@ -39,7 +38,11 @@ func lockedOpenFile(path string, flag int, perm os.FileMode, lockType int) (*Loc
 	case syscall.O_RDWR | syscall.O_CREAT:
 		lockType |= syscall.LOCK_EX
 	default:
-		return nil, fmt.Errorf("Unsupported flag (%d)", flag)
+		return nil, &os.PathError{
+			Op:   "open",
+			Path: path,
+			Err:  syscall.EINVAL,
+		}
 	}
 
 	f, err := os.OpenFile(path, flag|syscall.O_SYNC, perm)
diff --git a/pkg/lock/lock_solaris.go b/pkg/lock/lock_solaris.go
index a25c8bdd6..e20c6fe83 100644
--- a/pkg/lock/lock_solaris.go
+++ b/pkg/lock/lock_solaris.go
@@ -19,7 +19,6 @@
 package lock
 
 import (
-	"fmt"
 	"os"
 	"syscall"
 )
@@ -39,7 +38,11 @@ func lockedOpenFile(path string, flag int, perm os.FileMode, rlockType int) (*Lo
 	case syscall.O_RDWR | syscall.O_CREAT:
 		lockType = syscall.F_WRLCK
 	default:
-		return nil, fmt.Errorf("Unsupported flag (%d)", flag)
+		return nil, &os.PathError{
+			Op:   "open",
+			Path: path,
+			Err:  syscall.EINVAL,
+		}
 	}
 
 	var lock = syscall.Flock_t{