diff --git a/ja4plus.go b/ja4plus.go
index d362d59..1270d18 100644
--- a/ja4plus.go
+++ b/ja4plus.go
@@ -36,8 +36,8 @@ func JA4(hello *tls.ClientHelloInfo) string {
 	}
 
 	// Extract TLS version
-	supporetdVersions := slices.Sorted(slices.Values(hello.SupportedVersions))
-	switch supporetdVersions[len(supporetdVersions)-1] {
+	supportedVersions := slices.DeleteFunc(slices.Sorted(slices.Values(hello.SupportedVersions)), greaseFilter)
+	switch supportedVersions[len(supportedVersions)-1] {
 	case tls.VersionTLS10:
 		out = append(out, '1', '0')
 	case tls.VersionTLS11:
diff --git a/ja4plus_test.go b/ja4plus_test.go
index 31dcf02..6739b98 100644
--- a/ja4plus_test.go
+++ b/ja4plus_test.go
@@ -67,6 +67,14 @@ func TestJA4(t *testing.T) {
 			},
 			expected: "t13i0002h1_000000000000_5b56ea7744b1",
 		},
+		{
+			name: "ClientHelloInfo with grease values in SupportedVersions",
+			hello: &tls.ClientHelloInfo{
+				SupportedVersions: []uint16{tls.VersionTLS13, 0x1A1A /* GREASE */, tls.VersionTLS12, 0x2A2A /* GREASE */},
+				SupportedProtos:   []string{"http/1.1"},
+			},
+			expected: "t13i0000h1_000000000000_000000000000",
+		},
 	}
 
 	for _, tt := range tests {