diff --git a/packages/datasource-customizer/src/decorators/binary/collection.ts b/packages/datasource-customizer/src/decorators/binary/collection.ts
index 2f8652acbc..85a253c720 100644
--- a/packages/datasource-customizer/src/decorators/binary/collection.ts
+++ b/packages/datasource-customizer/src/decorators/binary/collection.ts
@@ -16,9 +16,17 @@ import type {
   RecordData,
 } from '@forestadmin/datasource-toolkit';
 
-import { CollectionDecorator, SchemaUtils, TypeGetter } from '@forestadmin/datasource-toolkit';
+import {
+  CollectionDecorator,
+  SchemaUtils,
+  TypeGetter,
+  ValidationError,
+  parseDataUri,
+} from '@forestadmin/datasource-toolkit';
 import { filetypemime } from 'magic-bytes.js';
 
+const HEX_BYTES = /^([0-9a-f]{2})+$/i;
+
 /**
  * As the transport layer between the forest admin agent and the frontend is JSON-API, binary data
  * is not supported.
@@ -237,15 +245,35 @@ export default class BinaryCollectionDecorator extends CollectionDecorator {
     return value;
   }
 
+  private parseHex(value: string): Buffer {
+    if (!HEX_BYTES.test(value)) {
+      throw new ValidationError(
+        `Expected a hex string of full bytes for a binary field, got "${value.slice(0, 32)}"`,
+      );
+    }
+
+    return Buffer.from(value, 'hex');
+  }
+
   private async convertScalar(
     toBackend: boolean,
     useHex: boolean,
     value: unknown,
   ): Promise<unknown> {
     if (toBackend) {
-      const string = value as string;
+      if (Buffer.isBuffer(value)) return value;
+
+      if (typeof value !== 'string') {
+        throw new ValidationError(
+          `Expected a string for a binary field, got ${typeof value}: ${JSON.stringify(
+            value,
+          )?.slice(0, 32)}`,
+        );
+      }
+
+      if (useHex) return this.parseHex(value);
 
-      return useHex ? Buffer.from(string, 'hex') : Buffer.from(string.split(',')[1], 'base64');
+      return parseDataUri(value).buffer;
     }
 
     const buffer = value as Buffer;
@@ -282,7 +310,7 @@ export default class BinaryCollectionDecorator extends CollectionDecorator {
       const maxLength = schema.validation?.find(v => v.operator === 'ShorterThan')?.value as number;
 
       if (this.shouldUseHex(name)) {
-        validation.push({ operator: 'Match', value: /^[0-9a-f]+$/ });
+        validation.push({ operator: 'Match', value: HEX_BYTES });
         if (minLength) validation.push({ operator: 'LongerThan', value: minLength * 2 + 1 });
         if (maxLength) validation.push({ operator: 'ShorterThan', value: maxLength * 2 - 1 });
       } else {
diff --git a/packages/datasource-customizer/test/decorators/binary/collection.test.ts b/packages/datasource-customizer/test/decorators/binary/collection.test.ts
index 5c773ec2a3..01dc87a1d6 100644
--- a/packages/datasource-customizer/test/decorators/binary/collection.test.ts
+++ b/packages/datasource-customizer/test/decorators/binary/collection.test.ts
@@ -109,7 +109,7 @@ describe('BinaryCollectionDecorator', () => {
           isPrimaryKey: true,
           columnType: 'String',
           validation: [
-            { operator: 'Match', value: /^[0-9a-f]+$/ },
+            { operator: 'Match', value: /^([0-9a-f]{2})+$/i },
             { operator: 'LongerThan', value: 31 },
             { operator: 'ShorterThan', value: 33 },
             { operator: 'Present' },
@@ -140,7 +140,7 @@ describe('BinaryCollectionDecorator', () => {
       expect(decoratedBook.schema.fields.cover).toEqual(
         expect.objectContaining({
           columnType: 'String',
-          validation: [{ operator: 'Match', value: /^[0-9a-f]+$/ }],
+          validation: [{ operator: 'Match', value: /^([0-9a-f]{2})+$/i }],
         }),
       );
     });
@@ -238,6 +238,61 @@ describe('BinaryCollectionDecorator', () => {
     });
   });
 
+  describe('list filtering a binary column with a malformed value', () => {
+    it.each([
+      ['cover', 'Anthony', /must be a data uri/],
+      ['cover', 'data:text/plain,hello', /must be a data uri/],
+      ['id', 'Anthony', /hex string of full bytes/],
+      ['id', '303', /hex string of full bytes/],
+    ])(
+      'should reject %s = %p instead of querying the collection',
+      async (field, value, message) => {
+        const caller = factories.caller.build();
+        const filter = new PaginatedFilter({
+          conditionTree: new ConditionTreeLeaf(field, 'Equal', value),
+        });
+
+        await expect(decoratedBook.list(caller, filter, new Projection('id'))).rejects.toThrow(
+          message,
+        );
+        expect(books.list).not.toHaveBeenCalled();
+      },
+    );
+
+    it('should truncate a long value in the error message', async () => {
+      const caller = factories.caller.build();
+      const filter = new PaginatedFilter({
+        conditionTree: new ConditionTreeLeaf('id', 'Equal', 'z'.repeat(5000)),
+      });
+
+      await expect(decoratedBook.list(caller, filter, new Projection('id'))).rejects.toThrow(
+        `Expected a hex string of full bytes for a binary field, got "${'z'.repeat(32)}"`,
+      );
+      expect(books.list).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('writing a non-string value into a binary column', () => {
+    it('should reject it with a validation error rather than an opaque TypeError', async () => {
+      const caller = factories.caller.build();
+
+      await expect(decoratedBook.create(caller, [{ cover: 42 }])).rejects.toThrow(
+        'Expected a string for a binary field, got number: 42',
+      );
+      expect(books.create).not.toHaveBeenCalled();
+    });
+
+    it('should let a buffer through, as it needs no conversion', async () => {
+      const caller = factories.caller.build();
+      const id = Buffer.from('0000', 'ascii');
+      (books.create as jest.Mock).mockResolvedValue([{ id }]);
+
+      await decoratedBook.create(caller, [{ id }]);
+
+      expect(books.create).toHaveBeenCalledWith(caller, [{ id }]);
+    });
+  });
+
   describe('list with a more complex filter', () => {
     // Build condition tree (30303030 is the hex representation of 0000)
     const conditionTree = new ConditionTreeBranch('Or', [