diff --git a/lint/extension_test.go b/lint/extension_test.go
new file mode 100644
index 0000000..481573c
--- /dev/null
+++ b/lint/extension_test.go
@@ -0,0 +1,52 @@
+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: BSD-3-Clause
+
+package lint
+
+import (
+	"testing"
+
+	"sourcedock.dev/petrbalvin/gasm-sdk/arch"
+	"sourcedock.dev/petrbalvin/gasm-sdk/asm"
+)
+
+// TestExtensionInstructionsAreKnown pins the lint side of the
+// extended-instruction layer: every mnemonic the arm64 registry carries
+// lints without unknown-instruction, and a kernel the encoder accepts lints
+// clean, because the wired layer is the acceptance rather than a gap of the
+// generated table.
+func TestExtensionInstructionsAreKnown(t *testing.T) {
+	src := `#include "textflag.h"
+TEXT ·f(SB), NOSPLIT, $0
+	ADD Z1.S, Z2.S, Z0.S
+	SUBR Z1.S, P0/M, Z0.S
+	SQADD Z0.D, Z1.D, Z2.D
+	UQADD Z0.D, Z1.D, Z2.D
+	SQSUB Z0.D, Z1.D, Z2.D
+	UQSUB Z0.D, Z1.D, Z2.D
+	SMULH Z3.D, Z4.D, Z5.D
+	ADD $255, Z0.S
+	MUL $-128, Z0.B
+	RET
+`
+	diags := lintArchFile(t, "ext_arm64.s", src, arch.ARM64, asm.AssembleFileARM64)
+	for _, code := range []string{CodeUnknownInstr, CodeUnencodable} {
+		if n := codes(diags)[code]; n != 0 {
+			t.Errorf("%s fired %d times on the wired extension: %+v", code, n, diags)
+		}
+	}
+	if len(diags) != 0 {
+		t.Errorf("a kernel the encoder accepts must lint clean, got %+v", diags)
+	}
+
+	// The registry consult is the layer's own, not a loosening of the rule:
+	// a mnemonic neither table nor registry carries still fires.
+	diags = lintSrcArch(t, "ext_arm64.s", `#include "textflag.h"
+TEXT ·f(SB), NOSPLIT, $0
+	FROBNICATE Z0.S, Z1.S, Z2.S
+	RET
+`)
+	if codes(diags)[CodeUnknownInstr] != 1 {
+		t.Errorf("an unregistered mnemonic must fire unknown-instruction once: %+v", diags)
+	}
+}
diff --git a/lint/lint.go b/lint/lint.go
index 2a2992d..6bf16ab 100644
--- a/lint/lint.go
+++ b/lint/lint.go
@@ -328,15 +328,23 @@ func lintText(t *ast.Text, tab *arch.Table, archKnown bool, cfg Config, macros m
 			}
 
 			if archKnown && !cfg.Disable[CodeUnknownInstr] && !pseudoOps[upper] && !isMacroInvocation(mnem, macros) {
+				// The extended-instruction layer is a mnemonic's second home:
+				// one registered there (arm64's SVE family today) is known,
+				// and it encodes through the extension registry rather than
+				// the encoder mirror the unencodable rule consults, so the
+				// wired extensions are never flagged as a gap of the table.
+				_, extended := asm.LookupExtension(cfg.Arch, mnem)
 				if _, ok := tab.Lookup(mnem); !ok {
-					out = append(out, Diagnostic{
-						Pos:      st.Mnemonic.Pos,
-						End:      st.Mnemonic.End,
-						Severity: Error,
-						Code:     CodeUnknownInstr,
-						Message:  fmt.Sprintf("unknown %s instruction %q", cfg.Arch, mnem),
-					})
-				} else if cfg.Arch == arch.AMD64 && !cfg.Disable[CodeUnencodable] && !asm.Encodable(upper) {
+					if !extended {
+						out = append(out, Diagnostic{
+							Pos:      st.Mnemonic.Pos,
+							End:      st.Mnemonic.End,
+							Severity: Error,
+							Code:     CodeUnknownInstr,
+							Message:  fmt.Sprintf("unknown %s instruction %q", cfg.Arch, mnem),
+						})
+					}
+				} else if cfg.Arch == arch.AMD64 && !extended && !cfg.Disable[CodeUnencodable] && !asm.Encodable(upper) {
 					// Known to the architecture table but missing from the
 					// encoder: the file parses everywhere and then fails at
 					// assembly time.  Flag it at lint so the gap is visible