diff --git a/src/cmd/internal/gc/lex.go b/src/cmd/internal/gc/lex.go
index edfb6ca7d7..c2c4207998 100644
--- a/src/cmd/internal/gc/lex.go
+++ b/src/cmd/internal/gc/lex.go
@@ -1865,20 +1865,21 @@ func getc() int {
 			curio.cp = curio.cp[1:]
 		}
 	} else {
-		var c1 int
-		var c2 int
 	loop:
 		c = obj.Bgetc(curio.bin)
 		if c == 0xef {
-			c1 = obj.Bgetc(curio.bin)
-			c2 = obj.Bgetc(curio.bin)
-			if c1 == 0xbb && c2 == 0xbf {
+			buf, err := curio.bin.Peek(2)
+			if err != nil {
+				log.Fatalf("getc: peeking: %v", err)
+			}
+			if buf[0] == 0xbb && buf[1] == 0xbf {
 				yyerrorl(int(lexlineno), "Unicode (UTF-8) BOM in middle of file")
+
+				// consume BOM bytes
+				obj.Bgetc(curio.bin)
+				obj.Bgetc(curio.bin)
 				goto loop
 			}
-
-			obj.Bungetc(curio.bin)
-			obj.Bungetc(curio.bin)
 		}
 	}
 
diff --git a/src/cmd/internal/obj/util.go b/src/cmd/internal/obj/util.go
index 71587954f4..b44b9caf38 100644
--- a/src/cmd/internal/obj/util.go
+++ b/src/cmd/internal/obj/util.go
@@ -28,12 +28,10 @@ func Cputime() float64 {
 }
 
 type Biobuf struct {
-	unget    [2]int
-	numUnget int
-	f        *os.File
-	r        *bufio.Reader
-	w        *bufio.Writer
-	linelen  int
+	f       *os.File
+	r       *bufio.Reader
+	w       *bufio.Writer
+	linelen int
 }
 
 func Bopenw(name string) (*Biobuf, error) {
@@ -116,18 +114,11 @@ func Bread(b *Biobuf, p []byte) int {
 }
 
 func Bgetc(b *Biobuf) int {
-	if b.numUnget > 0 {
-		b.numUnget--
-		return int(b.unget[b.numUnget])
-	}
 	c, err := b.r.ReadByte()
-	r := int(c)
 	if err != nil {
-		r = -1
+		return -1
 	}
-	b.unget[1] = b.unget[0]
-	b.unget[0] = r
-	return r
+	return int(c)
 }
 
 func Bgetrune(b *Biobuf) int {
@@ -146,6 +137,10 @@ func (b *Biobuf) Read(p []byte) (int, error) {
 	return b.r.Read(p)
 }
 
+func (b *Biobuf) Peek(n int) ([]byte, error) {
+	return b.r.Peek(n)
+}
+
 func Brdline(b *Biobuf, delim int) string {
 	s, err := b.r.ReadBytes(byte(delim))
 	if err != nil {
@@ -181,10 +176,6 @@ func Blinelen(b *Biobuf) int {
 	return b.linelen
 }
 
-func Bungetc(b *Biobuf) {
-	b.numUnget++
-}
-
 func Bterm(b *Biobuf) error {
 	var err error
 	if b.w != nil {