diff --git a/query/language_fuzz_test.go b/query/language_fuzz_test.go
new file mode 100644
index 0000000..821f88e
--- /dev/null
+++ b/query/language_fuzz_test.go
@@ -0,0 +1,97 @@
+package query
+
+import (
+	"testing"
+)
+
+// FuzzParse exercises the query DSL parser and normalizer with arbitrary input.
+// The goal is to ensure Parse never panics regardless of what a caller sends.
+//
+// Notable panic sites in normalize.go that the fuzzer can reach:
+//   - Expression.invert(): "This should never happen!" (via NOT-paren paths)
+//   - EqualExpr.Normalize(): "Called EqualExpr::Normalize on a paren, this is a bug!"
+//   - EqualExpr.Normalize(): "This should not happen!"
+//   - EqualExpr.invert():    "This should not happen!"
+func FuzzParse(f *testing.F) {
+	seeds := []string{
+		// match-all shortcuts
+		"$all",
+		"*",
+
+		// equality
+		`name = "value"`,
+		`name != "value"`,
+		`$key = 0xabcdef1234567890abcdef1234567890abcdef1234567890abcdef1234567890`,
+		`$owner = 0x1234567890abcdef1234567890abcdef12345678`,
+		`$creator = 0x1234567890abcdef1234567890abcdef12345678`,
+		`$expiration = 1000`,
+		`$sequence = 42`,
+
+		// comparisons (numeric and string)
+		`count > 5`,
+		`count >= 5`,
+		`count < 5`,
+		`count <= 5`,
+		`name > "bar"`,
+		`name >= "bar"`,
+
+		// glob
+		`name ~ "foo*"`,
+		`name !~ "foo*"`,
+		`name glob "foo*"`,
+		`name not glob "foo*"`,
+
+		// inclusion
+		`name IN ("a" "b" "c")`,
+		`name NOT IN ("a" "b")`,
+		`count IN (1 2 3)`,
+		`count NOT IN (1 2 3)`,
+
+		// boolean combinations
+		`name = "x" || other = "y"`,
+		`name = "x" && other = "y"`,
+		`name = "x" OR other = "y"`,
+		`name = "x" AND other = "y"`,
+		`name = "x" or other = "y"`,
+		`name = "x" and other = "y"`,
+
+		// parenthesised groups
+		`(name = "x")`,
+		`(name = "x" && other = "y")`,
+		`(name = "x" || other = "y") && third = "z"`,
+		`name = "a" && (b = "c" || d = "e")`,
+
+		// NOT-paren (exercises the invert() path in normalize.go)
+		`!(name = "value")`,
+		`not(name = "value")`,
+		`NOT(name = "value")`,
+		`!(name = "x" && other = "y")`,
+		`!(name = "x" || other = "y")`,
+		`!(!(name = "value"))`,
+		`!(name ~ "foo*")`,
+		`!(name IN ("a" "b"))`,
+		`!(count > 5)`,
+
+		// deeply nested
+		`((name = "x"))`,
+		`!((name = "x" || y = "z") && w = "v")`,
+		`(a = "1" || b = "2") && (c = "3" || d = "4")`,
+
+		// empty / near-empty
+		"",
+	}
+
+	for _, s := range seeds {
+		f.Add(s)
+	}
+
+	f.Fuzz(func(t *testing.T, input string) {
+		// Must not panic. Errors are fine — they represent rejected queries.
+		defer func() {
+			if r := recover(); r != nil {
+				t.Errorf("Parse panicked on input %q: %v", input, r)
+			}
+		}()
+		_, _ = Parse(input)
+	})
+}
diff --git a/query/normalize.go b/query/normalize.go
index 03afd96..62711a0 100644
--- a/query/normalize.go
+++ b/query/normalize.go
@@ -309,6 +309,9 @@ func (e *Glob) invert() *Glob {
 func (e *LessThan) Normalize() *LessThan {
 	switch e.Var {
 	case KeyAttributeKey, OwnerAttributeKey, CreatorAttributeKey:
+		if e.Value.String == nil {
+			return e
+		}
 		val := strings.ToLower(*e.Value.String)
 		return &LessThan{
 			Var: e.Var,
@@ -331,6 +334,9 @@ func (e *LessThan) invert() *GreaterOrEqualThan {
 func (e *LessOrEqualThan) Normalize() *LessOrEqualThan {
 	switch e.Var {
 	case KeyAttributeKey, OwnerAttributeKey, CreatorAttributeKey:
+		if e.Value.String == nil {
+			return e
+		}
 		val := strings.ToLower(*e.Value.String)
 		return &LessOrEqualThan{
 			Var: e.Var,
@@ -353,6 +359,9 @@ func (e *LessOrEqualThan) invert() *GreaterThan {
 func (e *GreaterThan) Normalize() *GreaterThan {
 	switch e.Var {
 	case KeyAttributeKey, OwnerAttributeKey, CreatorAttributeKey:
+		if e.Value.String == nil {
+			return e
+		}
 		val := strings.ToLower(*e.Value.String)
 		return &GreaterThan{
 			Var: e.Var,
@@ -375,6 +384,9 @@ func (e *GreaterThan) invert() *LessOrEqualThan {
 func (e *GreaterOrEqualThan) Normalize() *GreaterOrEqualThan {
 	switch e.Var {
 	case KeyAttributeKey, OwnerAttributeKey, CreatorAttributeKey:
+		if e.Value.String == nil {
+			return e
+		}
 		val := strings.ToLower(*e.Value.String)
 		return &GreaterOrEqualThan{
 			Var: e.Var,
@@ -397,6 +409,9 @@ func (e *GreaterOrEqualThan) invert() *LessThan {
 func (e *Equality) Normalize() *Equality {
 	switch e.Var {
 	case KeyAttributeKey, OwnerAttributeKey, CreatorAttributeKey:
+		if e.Value.String == nil {
+			return e
+		}
 		val := strings.ToLower(*e.Value.String)
 		return &Equality{
 			Var:   e.Var,
diff --git a/query/testdata/fuzz/FuzzParse/key_equals_number b/query/testdata/fuzz/FuzzParse/key_equals_number
new file mode 100644
index 0000000..2c81227
--- /dev/null
+++ b/query/testdata/fuzz/FuzzParse/key_equals_number
@@ -0,0 +1,2 @@
+go test fuzz v1
+string("$key =0")