diff --git a/src/core/jpg.js b/src/core/jpg.js
index c6111d74e..1ccb9aec1 100644
--- a/src/core/jpg.js
+++ b/src/core/jpg.js
@@ -958,12 +958,13 @@ var JpegImage = (function JpegImageClosure() {
       return data;
     },
 
-    _isColorConversionNeeded: function isColorConversionNeeded() {
-      if (this.adobe && this.adobe.transformCode) {
-        // The adobe transform marker overrides any previous setting
-        return true;
-      } else if (this.numComponents === 3) {
-        if (!this.adobe && this.colorTransform === 0) {
+    _isColorConversionNeeded() {
+      if (this.adobe) {
+        // The adobe transform marker overrides any previous setting.
+        return !!this.adobe.transformCode;
+      }
+      if (this.numComponents === 3) {
+        if (this.colorTransform === 0) {
           // If the Adobe transform marker is not present and the image
           // dictionary has a 'ColorTransform' entry, explicitly set to `0`,
           // then the colours should *not* be transformed.
@@ -972,7 +973,7 @@ var JpegImage = (function JpegImageClosure() {
         return true;
       }
       // `this.numComponents !== 3`
-      if (!this.adobe && this.colorTransform === 1) {
+      if (this.colorTransform === 1) {
         // If the Adobe transform marker is not present and the image
         // dictionary has a 'ColorTransform' entry, explicitly set to `1`,
         // then the colours should be transformed.
diff --git a/test/driver.js b/test/driver.js
index 5ddaca848..818be019d 100644
--- a/test/driver.js
+++ b/test/driver.js
@@ -358,6 +358,7 @@ var Driver = (function DriverClosure() { // eslint-disable-line no-unused-vars
           PDFJS.getDocument({
             url: absoluteUrl,
             password: task.password,
+            nativeImageDecoderSupport: task.nativeImageDecoderSupport,
           }).then((doc) => {
             task.pdfDoc = doc;
             this._nextPage(task, failure);
diff --git a/test/test_manifest.json b/test/test_manifest.json
index 5a4006507..92ee604d6 100644
--- a/test/test_manifest.json
+++ b/test/test_manifest.json
@@ -3378,6 +3378,15 @@
        "link": true,
        "type": "eq"
     },
+    {  "id": "issue4926-built-in-jpg",
+       "file": "pdfs/issue4926.pdf",
+       "md5": "ed881c8ea2f9bc4be94ecb7f2b2c149b",
+       "rounds": 1,
+       "link": true,
+       "lastPage": 1,
+       "type": "eq",
+       "nativeImageDecoderSupport": "none"
+    },
     {  "id": "issue5592",
        "file": "pdfs/issue5592.pdf",
        "md5": "a0750f95afa80c880f7966df7062616c",