diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go
index 708980bc1c31be..7c5ac86c0a1aa8 100644
--- a/src/debug/elf/file.go
+++ b/src/debug/elf/file.go
@@ -467,8 +467,12 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	}
 
 	// Read section headers
-	f.Sections = make([]*Section, shnum)
-	names := make([]uint32, shnum)
+	c := saferio.SliceCap((*Section)(nil), uint64(shnum))
+	if c < 0 {
+		return nil, &FormatError{0, "too many sections", shnum}
+	}
+	f.Sections = make([]*Section, 0, c)
+	names := make([]uint32, 0, c)
 	for i := 0; i < shnum; i++ {
 		off := shoff + int64(i)*int64(shentsize)
 		sr.Seek(off, seekStart)
@@ -479,7 +483,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			if err := binary.Read(sr, f.ByteOrder, sh); err != nil {
 				return nil, err
 			}
-			names[i] = sh.Name
+			names = append(names, sh.Name)
 			s.SectionHeader = SectionHeader{
 				Type:      SectionType(sh.Type),
 				Flags:     SectionFlag(sh.Flags),
@@ -496,7 +500,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			if err := binary.Read(sr, f.ByteOrder, sh); err != nil {
 				return nil, err
 			}
-			names[i] = sh.Name
+			names = append(names, sh.Name)
 			s.SectionHeader = SectionHeader{
 				Type:      SectionType(sh.Type),
 				Flags:     SectionFlag(sh.Flags),
@@ -544,7 +548,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			}
 		}
 
-		f.Sections[i] = s
+		f.Sections = append(f.Sections, s)
 	}
 
 	if len(f.Sections) == 0 {