diff --git a/packages/data-provider/src/file-config.spec.ts b/packages/data-provider/src/file-config.spec.ts
index ee894712ff..ec846af5a4 100644
--- a/packages/data-provider/src/file-config.spec.ts
+++ b/packages/data-provider/src/file-config.spec.ts
@@ -19,6 +19,10 @@ describe('inferMimeType', () => {
     expect(inferMimeType('test.py', 'text/x-python-script')).toBe('text/x-python');
   });
 
+  it('should normalize text/x-markdown to text/markdown', () => {
+    expect(inferMimeType('test.md', 'text/x-markdown')).toBe('text/markdown');
+  });
+
   it('should return a type that matches textMimeTypes after normalization', () => {
     const normalized = inferMimeType('test.py', 'text/x-python-script');
     expect(textMimeTypes.test(normalized)).toBe(true);
@@ -45,9 +49,18 @@ describe('inferMimeType', () => {
     expect(baseFileConfig.checkType(normalized)).toBe(true);
   });
 
+  it('should produce a type accepted by checkType after normalizing text/x-markdown', () => {
+    const normalized = inferMimeType('test.md', 'text/x-markdown');
+    expect(baseFileConfig.checkType(normalized)).toBe(true);
+  });
+
   it('should reject raw text/x-python-script without normalization', () => {
     expect(baseFileConfig.checkType('text/x-python-script')).toBe(false);
   });
+
+  it('should reject raw text/x-markdown without normalization', () => {
+    expect(baseFileConfig.checkType('text/x-markdown')).toBe(false);
+  });
 });
 
 describe('applicationMimeTypes', () => {
diff --git a/packages/data-provider/src/file-config.ts b/packages/data-provider/src/file-config.ts
index a93daf79e2..2a29b46943 100644
--- a/packages/data-provider/src/file-config.ts
+++ b/packages/data-provider/src/file-config.ts
@@ -362,6 +362,7 @@ export const imageTypeMapping: { [key: string]: string } = {
 /** Normalizes non-standard MIME types that browsers may report to their canonical forms */
 export const mimeTypeAliases: Readonly<Record<string, string>> = {
   'text/x-python-script': 'text/x-python',
+  'text/x-markdown': 'text/markdown',
 };
 
 /**