diff --git a/perflib/perflib.go b/perflib/perflib.go
index 2b3c462d..399de3fd 100644
--- a/perflib/perflib.go
+++ b/perflib/perflib.go
@@ -173,7 +173,7 @@ type PerfCounter struct {
 }
 
 // Error value returned by RegQueryValueEx if the buffer isn't sufficiently large
-const errorMoreData = syscall.Errno(234)
+const errorMoreData = syscall.Errno(syscall.ERROR_MORE_DATA)
 
 var (
 	bufLenGlobal = uint32(400000)
@@ -209,8 +209,6 @@ func queryRawData(query string) ([]byte, error) {
 		return nil, fmt.Errorf("failed to encode query string: %v", err)
 	}
 
-	defer syscall.RegCloseKey(syscall.HKEY_PERFORMANCE_DATA)
-
 	for {
 		bufLen := uint32(len(buffer))
 
@@ -226,7 +224,6 @@ func queryRawData(query string) ([]byte, error) {
 			newBuffer := make([]byte, len(buffer)+16384)
 			copy(newBuffer, buffer)
 			buffer = newBuffer
-			syscall.RegCloseKey(syscall.HKEY_PERFORMANCE_DATA)
 			continue
 		} else if err != nil {
 			if errno, ok := err.(syscall.Errno); ok {
diff --git a/perflib/raw_types.go b/perflib/raw_types.go
index f9d76a7d..5939b7da 100644
--- a/perflib/raw_types.go
+++ b/perflib/raw_types.go
@@ -6,10 +6,6 @@ import (
 	"syscall"
 )
 
-type binaryReaderFrom interface {
-	BinaryReadFrom(r io.Reader) error
-}
-
 /*
 perfDataBlock
 See: https://msdn.microsoft.com/de-de/library/windows/desktop/aa373157(v=vs.85).aspx