diff --git a/cmd/gsap-attestor/attestor_test.go b/cmd/gsap-attestor/attestor_test.go
index 1468d02..5c210a3 100644
--- a/cmd/gsap-attestor/attestor_test.go
+++ b/cmd/gsap-attestor/attestor_test.go
@@ -367,6 +367,34 @@ func TestAttest_EndToEnd_CapabilityMask(t *testing.T) {
 	assertSelector(t, smap, "capability_mask", "0x0f")
 }
 
+// --- decodeConfig tests ---
+
+func TestDecodeConfig_SPIREFormat(t *testing.T) {
+	// SPIRE converts JSON plugin_data to HCL v1 native syntax with quoted keys
+	input := "\"max_depth\" = 10\n\n\"proc_root\" = \"/proc\""
+	cfg, err := decodeConfig(input)
+	if err != nil {
+		t.Fatalf("decodeConfig failed on SPIRE format: %v", err)
+	}
+	if cfg.MaxDepth != 10 {
+		t.Errorf("max_depth = %d, want 10", cfg.MaxDepth)
+	}
+	if cfg.ProcRoot != "/proc" {
+		t.Errorf("proc_root = %q, want /proc", cfg.ProcRoot)
+	}
+}
+
+func TestDecodeConfig_NativeHCL(t *testing.T) {
+	input := "max_depth = 10\nproc_root = \"/proc\""
+	cfg, err := decodeConfig(input)
+	if err != nil {
+		t.Fatalf("decodeConfig failed on native HCL: %v", err)
+	}
+	if cfg.MaxDepth != 10 || cfg.ProcRoot != "/proc" {
+		t.Errorf("unexpected config: %+v", cfg)
+	}
+}
+
 // --- test helpers ---
 
 func selectorMap(selectors []string) map[string]string {
diff --git a/cmd/gsap-attestor/main.go b/cmd/gsap-attestor/main.go
index 7598344..d23753b 100644
--- a/cmd/gsap-attestor/main.go
+++ b/cmd/gsap-attestor/main.go
@@ -2,7 +2,7 @@ package main
 
 import (
 	"context"
-	"fmt"
+	"regexp"
 	"sync"
 
 	"github.com/hashicorp/hcl/v2/hclsimple"
@@ -40,17 +40,19 @@ func (p *Plugin) Attest(ctx context.Context, req *workloadattestorv1.AttestReque
 	}, nil
 }
 
+// unquoteHCLKeys strips quotes from HCL v1-style attribute names
+// (e.g. `"max_depth" = 10` → `max_depth = 10`). SPIRE converts JSON
+// plugin_data to HCL v1 native syntax which uses quoted keys that
+// HCL v2's parser rejects.
+var hclQuotedKey = regexp.MustCompile(`(?m)^(\s*)"([a-zA-Z_][a-zA-Z0-9_]*)"(\s*=)`)
+
 func decodeConfig(data string) (GsapAttestorConfig, error) {
 	var cfg GsapAttestorConfig
-	jsonErr := hclsimple.Decode("plugin.json", []byte(data), nil, &cfg)
-	if jsonErr == nil {
-		return cfg, nil
+	normalized := hclQuotedKey.ReplaceAllString(data, `${1}${2}${3}`)
+	if err := hclsimple.Decode("plugin.hcl", []byte(normalized), nil, &cfg); err != nil {
+		return cfg, err
 	}
-	hclErr := hclsimple.Decode("plugin.hcl", []byte(data), nil, &cfg)
-	if hclErr == nil {
-		return cfg, nil
-	}
-	return cfg, fmt.Errorf("json: %v; hcl: %v; raw input: %q", jsonErr, hclErr, data)
+	return cfg, nil
 }
 
 func (p *Plugin) Configure(_ context.Context, req *configv1.ConfigureRequest) (*configv1.ConfigureResponse, error) {