diff --git a/src/cmd/link/internal/arm64/asm.go b/src/cmd/link/internal/arm64/asm.go
index a7af855646..30819db4c6 100644
--- a/src/cmd/link/internal/arm64/asm.go
+++ b/src/cmd/link/internal/arm64/asm.go
@@ -463,6 +463,9 @@ func elfreloc1(ctxt *ld.Link, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym,
 	return true
 }
 
+// sign-extends from 24-bit.
+func signext24(x int64) int64 { return x << 40 >> 40 }
+
 func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sym, r loader.ExtReloc, sectoff int64) bool {
 	var v uint32
 
@@ -486,6 +489,10 @@ func machoreloc1(arch *sys.Arch, out *ld.OutBuf, ldr *loader.Loader, s loader.Sy
 		}
 	}
 
+	if r.Xadd != signext24(r.Xadd) {
+		ldr.Errorf(s, "relocation addend overflow: %s+0x%x", ldr.SymName(rs), r.Xadd)
+	}
+
 	switch rt {
 	default:
 		return false