diff --git a/src/core/colorspace.js b/src/core/colorspace.js
index 7f0a301e1..354dadbf8 100644
--- a/src/core/colorspace.js
+++ b/src/core/colorspace.js
@@ -1280,18 +1280,57 @@ class CalRGBCS extends ColorSpace {
  *
  * The default color is `new Float32Array([0, 0, 0])`.
  */
-const LabCS = (function LabCSClosure() {
+class LabCS extends ColorSpace {
+  constructor(whitePoint, blackPoint, range) {
+    super("Lab", 3);
+
+    if (!whitePoint) {
+      throw new FormatError(
+        "WhitePoint missing - required for color space Lab"
+      );
+    }
+    // Translate args to spec variables
+    [this.XW, this.YW, this.ZW] = whitePoint;
+    [this.amin, this.amax, this.bmin, this.bmax] = range || [
+      -100, 100, -100, 100,
+    ];
+
+    // These are here just for completeness - the spec doesn't offer any
+    // formulas that use BlackPoint in Lab
+    [this.XB, this.YB, this.ZB] = blackPoint || [0, 0, 0];
+
+    // Validate vars as per spec
+    if (this.XW < 0 || this.ZW < 0 || this.YW !== 1) {
+      throw new FormatError(
+        "Invalid WhitePoint components, no fallback available"
+      );
+    }
+
+    if (this.XB < 0 || this.YB < 0 || this.ZB < 0) {
+      info("Invalid BlackPoint, falling back to default");
+      this.XB = this.YB = this.ZB = 0;
+    }
+
+    if (this.amin > this.amax || this.bmin > this.bmax) {
+      info("Invalid Range, falling back to defaults");
+      this.amin = -100;
+      this.amax = 100;
+      this.bmin = -100;
+      this.bmax = 100;
+    }
+  }
+
   // Function g(x) from spec
-  function fn_g(x) {
+  #fn_g(x) {
     return x >= 6 / 29 ? x ** 3 : (108 / 841) * (x - 4 / 29);
   }
 
-  function decode(value, high1, low2, high2) {
+  #decode(value, high1, low2, high2) {
     return low2 + (value * (high2 - low2)) / high1;
   }
 
   // If decoding is needed maxVal should be 2^bits per component - 1.
-  function convertToRgb(cs, src, srcOffset, maxVal, dest, destOffset) {
+  #toRgb(src, srcOffset, maxVal, dest, destOffset) {
     // XXX: Lab input is in the range of [0, 100], [amin, amax], [bmin, bmax]
     // not the usual [0, 1]. If a command like setFillColor is used the src
     // values will already be within the correct range. However, if we are
@@ -1302,21 +1341,21 @@ const LabCS = (function LabCSClosure() {
     let as = src[srcOffset + 1];
     let bs = src[srcOffset + 2];
     if (maxVal !== false) {
-      Ls = decode(Ls, maxVal, 0, 100);
-      as = decode(as, maxVal, cs.amin, cs.amax);
-      bs = decode(bs, maxVal, cs.bmin, cs.bmax);
+      Ls = this.#decode(Ls, maxVal, 0, 100);
+      as = this.#decode(as, maxVal, this.amin, this.amax);
+      bs = this.#decode(bs, maxVal, this.bmin, this.bmax);
     }
 
     // Adjust limits of 'as' and 'bs'
-    if (as > cs.amax) {
-      as = cs.amax;
-    } else if (as < cs.amin) {
-      as = cs.amin;
+    if (as > this.amax) {
+      as = this.amax;
+    } else if (as < this.amin) {
+      as = this.amin;
     }
-    if (bs > cs.bmax) {
-      bs = cs.bmax;
-    } else if (bs < cs.bmin) {
-      bs = cs.bmin;
+    if (bs > this.bmax) {
+      bs = this.bmax;
+    } else if (bs < this.bmin) {
+      bs = this.bmin;
     }
 
     // Computes intermediate variables X,Y,Z as per spec
@@ -1324,14 +1363,14 @@ const LabCS = (function LabCSClosure() {
     const L = M + as / 500;
     const N = M - bs / 200;
 
-    const X = cs.XW * fn_g(L);
-    const Y = cs.YW * fn_g(M);
-    const Z = cs.ZW * fn_g(N);
+    const X = this.XW * this.#fn_g(L);
+    const Y = this.YW * this.#fn_g(M);
+    const Z = this.ZW * this.#fn_g(N);
 
     let r, g, b;
     // Using different conversions for D50 and D65 white points,
     // per http://www.color.org/srgb.pdf
-    if (cs.ZW < 1) {
+    if (this.ZW < 1) {
       // Assuming D50 (X=0.9642, Y=1.00, Z=0.8249)
       r = X * 3.1339 + Y * -1.617 + Z * -0.4906;
       g = X * -0.9785 + Y * 1.916 + Z * 0.0333;
@@ -1348,95 +1387,44 @@ const LabCS = (function LabCSClosure() {
     dest[destOffset + 2] = Math.sqrt(b) * 255;
   }
 
-  // eslint-disable-next-line no-shadow
-  class LabCS extends ColorSpace {
-    constructor(whitePoint, blackPoint, range) {
-      super("Lab", 3);
-
-      if (!whitePoint) {
-        throw new FormatError(
-          "WhitePoint missing - required for color space Lab"
-        );
-      }
-      blackPoint ||= [0, 0, 0];
-      range ||= [-100, 100, -100, 100];
-
-      // Translate args to spec variables
-      this.XW = whitePoint[0];
-      this.YW = whitePoint[1];
-      this.ZW = whitePoint[2];
-      this.amin = range[0];
-      this.amax = range[1];
-      this.bmin = range[2];
-      this.bmax = range[3];
-
-      // These are here just for completeness - the spec doesn't offer any
-      // formulas that use BlackPoint in Lab
-      this.XB = blackPoint[0];
-      this.YB = blackPoint[1];
-      this.ZB = blackPoint[2];
-
-      // Validate vars as per spec
-      if (this.XW < 0 || this.ZW < 0 || this.YW !== 1) {
-        throw new FormatError(
-          "Invalid WhitePoint components, no fallback available"
-        );
-      }
-
-      if (this.XB < 0 || this.YB < 0 || this.ZB < 0) {
-        info("Invalid BlackPoint, falling back to default");
-        this.XB = this.YB = this.ZB = 0;
-      }
-
-      if (this.amin > this.amax || this.bmin > this.bmax) {
-        info("Invalid Range, falling back to defaults");
-        this.amin = -100;
-        this.amax = 100;
-        this.bmin = -100;
-        this.bmax = 100;
-      }
+  getRgbItem(src, srcOffset, dest, destOffset) {
+    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
+      assert(
+        dest instanceof Uint8ClampedArray,
+        'LabCS.getRgbItem: Unsupported "dest" type.'
+      );
     }
+    this.#toRgb(src, srcOffset, false, dest, destOffset);
+  }
 
-    getRgbItem(src, srcOffset, dest, destOffset) {
-      if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
-        assert(
-          dest instanceof Uint8ClampedArray,
-          'LabCS.getRgbItem: Unsupported "dest" type.'
-        );
-      }
-      convertToRgb(this, src, srcOffset, false, dest, destOffset);
+  getRgbBuffer(src, srcOffset, count, dest, destOffset, bits, alpha01) {
+    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
+      assert(
+        dest instanceof Uint8ClampedArray,
+        'LabCS.getRgbBuffer: Unsupported "dest" type.'
+      );
     }
-
-    getRgbBuffer(src, srcOffset, count, dest, destOffset, bits, alpha01) {
-      if (typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING")) {
-        assert(
-          dest instanceof Uint8ClampedArray,
-          'LabCS.getRgbBuffer: Unsupported "dest" type.'
-        );
-      }
-      const maxVal = (1 << bits) - 1;
-      for (let i = 0; i < count; i++) {
-        convertToRgb(this, src, srcOffset, maxVal, dest, destOffset);
-        srcOffset += 3;
-        destOffset += 3 + alpha01;
-      }
-    }
-
-    getOutputLength(inputLength, alpha01) {
-      return ((inputLength * (3 + alpha01)) / 3) | 0;
-    }
-
-    isDefaultDecode(decodeMap, bpc) {
-      // XXX: Decoding is handled with the lab conversion because of the strange
-      // ranges that are used.
-      return true;
-    }
-
-    get usesZeroToOneRange() {
-      return shadow(this, "usesZeroToOneRange", false);
+    const maxVal = (1 << bits) - 1;
+    for (let i = 0; i < count; i++) {
+      this.#toRgb(src, srcOffset, maxVal, dest, destOffset);
+      srcOffset += 3;
+      destOffset += 3 + alpha01;
     }
   }
-  return LabCS;
-})();
+
+  getOutputLength(inputLength, alpha01) {
+    return ((inputLength * (3 + alpha01)) / 3) | 0;
+  }
+
+  isDefaultDecode(decodeMap, bpc) {
+    // XXX: Decoding is handled with the lab conversion because of the strange
+    // ranges that are used.
+    return true;
+  }
+
+  get usesZeroToOneRange() {
+    return shadow(this, "usesZeroToOneRange", false);
+  }
+}
 
 export { ColorSpace };