diff --git a/lambda_test.go b/lambda_test.go
new file mode 100644
index 0000000..c1a4b20
--- /dev/null
+++ b/lambda_test.go
@@ -0,0 +1,43 @@
+package vfilter
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type lambdaTest struct {
+	name, clause string
+	result       Any
+	input        Any
+}
+
+var lambdaTestCases = []lambdaTest{
+	{
+		name:   "Simple Lambda",
+		clause: "x=>1+1",
+		input:  1,
+		result: 2,
+	},
+	{
+		name:   "Complex Lambda",
+		clause: "x=> 1 + 0x0aB",
+		input:  1,
+		result: 172,
+	},
+}
+
+func TestLambda(t *testing.T) {
+	scope := makeScope()
+	for _, test := range lambdaTestCases {
+		lambda, err := ParseLambda(test.clause)
+		assert.NoError(t, err)
+
+		res := lambda.Reduce(
+			context.Background(), scope, []Any{test.input})
+		if !scope.Eq(test.result, res) {
+			t.Fatalf("%v: %v != %v", test.name, test.result, res)
+		}
+	}
+}
diff --git a/vfilter.go b/vfilter.go
index 1636f9f..29dbbdb 100644
--- a/vfilter.go
+++ b/vfilter.go
@@ -169,7 +169,7 @@ var (
 		{Name: "ORDERBY", Pattern: `(?i)\bORDER\s+BY\b`},
 		{Name: "BOOL", Pattern: `(?i)\bTRUE\b|\bFALSE\b`},
 		{Name: "LET", Pattern: `(?i)\bLET\b`},
-		{Name: "Number", Pattern: `-?(0x[0-9a-f]+|\d*\.?\d+([eE][-+]?\d+)?)`},
+		{Name: "Number", Pattern: `-?(0x[0-9a-fA-F]+|\d*\.?\d+([eE][-+]?\d+)?)`},
 		{Name: "Ident", Pattern: `[a-zA-Z_][a-zA-Z0-9_]*|` + "`[^`]+`"},
 		{Name: "SymbolIdent", Pattern: `-[a-zA-Z_][a-zA-Z0-9_]*|-` + "`[^`]+`"},
 		{Name: "Operators", Pattern: `<>|!=|<=|>=|=>|=~|[-]|[+]|[:*/%,.()=<>{}\[\]]`},