diff --git a/src/encode-trie.ts b/src/encode-trie.ts
index e98273da..bb3d3025 100644
--- a/src/encode-trie.ts
+++ b/src/encode-trie.ts
@@ -1,5 +1,14 @@
 import htmlMap from "./maps/entities.json";
 
+const enum Surrogate {
+    Mask = 0b1111_1100_0000_0000,
+    High = 0b1101_1000_0000_0000,
+}
+
+function isHighSurrugate(c: number) {
+    return (c & Surrogate.Mask) === Surrogate.High;
+}
+
 // For compatibility with node < 4, we wrap `codePointAt`
 export const getCodePoint =
     // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
@@ -7,8 +16,8 @@ export const getCodePoint =
         ? (str: string, index: number): number => str.codePointAt(index)!
         : // http://mathiasbynens.be/notes/javascript-encoding#surrogate-formulae
           (c: string, index: number): number =>
-              (c.charCodeAt(index) & 0xd800) === 0xd800
-                  ? (c.charCodeAt(index) - 0xd800) * 0x400 +
+              isHighSurrugate(c.charCodeAt(index))
+                  ? (c.charCodeAt(index) - Surrogate.High) * 0x400 +
                     c.charCodeAt(index + 1) -
                     0xdc00 +
                     0x10000
@@ -45,7 +54,7 @@ export function encodeHTMLTrieRe(regExp: RegExp, str: string): string {
                 i
             ).toString(16)};`;
             // Increase by 1 if we have a surrogate pair
-            lastIdx = regExp.lastIndex += Number((char & 0xd800) === 0xd800);
+            lastIdx = regExp.lastIndex += Number(isHighSurrugate(char));
         }
     }
 
diff --git a/src/encode.spec.ts b/src/encode.spec.ts
index cecb92b2..a0c0c89c 100644
--- a/src/encode.spec.ts
+++ b/src/encode.spec.ts
@@ -54,4 +54,11 @@ describe("encodeNonAsciiHTML", () => {
         expect(entities.encodeNonAsciiHTML("😄🍾🥳💥😇")).toBe(
             "&#x1f604;&#x1f37e;&#x1f973;&#x1f4a5;&#x1f607;"
         ));
+
+    it("should encode chars above surrogates", () =>
+        expect(
+            entities.encodeNonAsciiHTML("♒️♓️♈️♉️♊️♋️♌️♍️♎️♏️♐️♑️")
+        ).toBe(
+            "&#x2652;&#xfe0f;&#x2653;&#xfe0f;&#x2648;&#xfe0f;&#x2649;&#xfe0f;&#x264a;&#xfe0f;&#x264b;&#xfe0f;&#x264c;&#xfe0f;&#x264d;&#xfe0f;&#x264e;&#xfe0f;&#x264f;&#xfe0f;&#x2650;&#xfe0f;&#x2651;&#xfe0f;"
+        ));
 });
diff --git a/src/encode.ts b/src/encode.ts
index 871fc7a1..b5253607 100644
--- a/src/encode.ts
+++ b/src/encode.ts
@@ -41,7 +41,7 @@ export function encodeXML(str: string): string {
             ).toString(16)};`;
             // Increase by 1 if we have a surrogate pair
             lastIdx = xmlReplacer.lastIndex += Number(
-                (char & 0xd800) === 0xd800
+                (char & 0b1111_1111_1000_0000) === 0xd800
             );
         }
     }