diff --git a/index.ts b/index.ts
index efcb58e7b..fff80ec1c 100644
--- a/index.ts
+++ b/index.ts
@@ -103,6 +103,7 @@ export * from './src/storage/Conditions';
 export * from './src/storage/ContainerManager';
 export * from './src/storage/DataAccessorBasedStore';
 export * from './src/storage/ExtensionBasedMapper';
+export * from './src/storage/FixedConvertingStore';
 export * from './src/storage/Lock';
 export * from './src/storage/LockingResourceStore';
 export * from './src/storage/PassthroughStore';
diff --git a/src/storage/FixedConvertingStore.ts b/src/storage/FixedConvertingStore.ts
new file mode 100644
index 000000000..4a675dee2
--- /dev/null
+++ b/src/storage/FixedConvertingStore.ts
@@ -0,0 +1,45 @@
+import type { Representation } from '../ldp/representation/Representation';
+import type { RepresentationPreference } from '../ldp/representation/RepresentationPreference';
+import type { ResourceIdentifier } from '../ldp/representation/ResourceIdentifier';
+import type { Conditions } from './Conditions';
+import type { RepresentationConverter } from './conversion/RepresentationConverter';
+import { PassthroughStore } from './PassthroughStore';
+import type { ResourceStore } from './ResourceStore';
+
+/**
+ * Store that converts incoming data when required.
+ * If the content-type of an incoming representation does not match one of the stored types it will be converted.
+ */
+export class FixedConvertingStore extends PassthroughStore {
+  private readonly types: string[];
+  private readonly converter: RepresentationConverter;
+
+  public constructor(source: ResourceStore, converter: RepresentationConverter, types: string[]) {
+    super(source);
+    this.converter = converter;
+    this.types = types;
+  }
+
+  public async addResource(container: ResourceIdentifier, representation: Representation,
+    conditions?: Conditions): Promise<ResourceIdentifier> {
+    // We can potentially run into problems here if we convert a turtle document where the base IRI is required,
+    // since we don't know the resource IRI yet at this point.
+    representation = await this.convertRepresentation(container, representation);
+    return this.source.addResource(container, representation, conditions);
+  }
+
+  public async setRepresentation(identifier: ResourceIdentifier, representation: Representation,
+    conditions?: Conditions): Promise<void> {
+    representation = await this.convertRepresentation(identifier, representation);
+    return this.source.setRepresentation(identifier, representation, conditions);
+  }
+
+  private async convertRepresentation(identifier: ResourceIdentifier, representation: Representation):
+  Promise<Representation> {
+    if (this.types.includes(representation.metadata.contentType!)) {
+      return representation;
+    }
+    const preferences = this.types.map((type): RepresentationPreference => ({ value: type, weight: 1 }));
+    return this.converter.handleSafe({ identifier, representation, preferences: { type: preferences }});
+  }
+}
diff --git a/src/storage/accessors/SparqlDataAccessor.ts b/src/storage/accessors/SparqlDataAccessor.ts
index 441f451d8..e72454720 100644
--- a/src/storage/accessors/SparqlDataAccessor.ts
+++ b/src/storage/accessors/SparqlDataAccessor.ts
@@ -20,6 +20,7 @@ import type { ResourceIdentifier } from '../../ldp/representation/ResourceIdenti
 import { INTERNAL_QUADS } from '../../util/ContentTypes';
 import { ConflictHttpError } from '../../util/errors/ConflictHttpError';
 import { NotFoundHttpError } from '../../util/errors/NotFoundHttpError';
+import { UnsupportedHttpError } from '../../util/errors/UnsupportedHttpError';
 import { UnsupportedMediaTypeHttpError } from '../../util/errors/UnsupportedMediaTypeHttpError';
 import type { MetadataController } from '../../util/MetadataController';
 import { CONTENT_TYPE, LDP } from '../../util/UriConstants';
@@ -28,7 +29,7 @@ import { ensureTrailingSlash } from '../../util/Util';
 import type { ContainerManager } from '../ContainerManager';
 import type { DataAccessor } from './DataAccessor';
 
-const { quad, namedNode, variable } = DataFactory;
+const { defaultGraph, namedNode, quad, variable } = DataFactory;
 
 /**
  * Stores all data and metadata of resources in a SPARQL backend.
@@ -124,10 +125,16 @@ export class SparqlDataAccessor implements DataAccessor {
     }
     const { name, parent } = await this.getRelevantNames(identifier);
 
+    const triples = await arrayifyStream(data) as Quad[];
+    const def = defaultGraph();
+    if (triples.some((triple): boolean => !triple.graph.equals(def))) {
+      throw new UnsupportedHttpError('Only triples in the default graph are supported.');
+    }
+
     // Not relevant since all content is triples
     metadata.removeAll(CONTENT_TYPE);
 
-    return this.sendSparqlUpdate(this.sparqlInsert(name, parent, metadata, await arrayifyStream(data)));
+    return this.sendSparqlUpdate(this.sparqlInsert(name, parent, metadata, triples));
   }
 
   /**
diff --git a/test/unit/storage/FixedConvertingStore.test.ts b/test/unit/storage/FixedConvertingStore.test.ts
new file mode 100644
index 000000000..f1afca71e
--- /dev/null
+++ b/test/unit/storage/FixedConvertingStore.test.ts
@@ -0,0 +1,51 @@
+import type { Representation } from '../../../src/ldp/representation/Representation';
+import { RepresentationMetadata } from '../../../src/ldp/representation/RepresentationMetadata';
+import type { RepresentationConverter } from '../../../src/storage/conversion/RepresentationConverter';
+import { FixedConvertingStore } from '../../../src/storage/FixedConvertingStore';
+import type { ResourceStore } from '../../../src/storage/ResourceStore';
+import { StaticAsyncHandler } from '../../util/StaticAsyncHandler';
+
+describe('A FixedConvertingStore', (): void => {
+  let store: FixedConvertingStore;
+  let source: ResourceStore;
+  let converter: RepresentationConverter;
+  const types = [ 'text/turtle' ];
+  let metadata: RepresentationMetadata;
+  let representation: Representation;
+
+  beforeEach(async(): Promise<void> => {
+    source = {
+      addResource: jest.fn(),
+      setRepresentation: jest.fn(),
+    } as any;
+
+    converter = new StaticAsyncHandler(true, 'converted') as any;
+
+    store = new FixedConvertingStore(source, converter, types);
+
+    metadata = new RepresentationMetadata();
+    representation = { binary: true, data: 'data', metadata } as any;
+  });
+
+  it('keeps the representation if the content-type is supported.', async(): Promise<void> => {
+    metadata.contentType = types[0];
+    const id = { path: 'identifier' };
+
+    await expect(store.addResource(id, representation, 'conditions' as any)).resolves.toBeUndefined();
+    expect(source.addResource).toHaveBeenLastCalledWith(id, representation, 'conditions');
+
+    await expect(store.setRepresentation(id, representation, 'conditions' as any)).resolves.toBeUndefined();
+    expect(source.setRepresentation).toHaveBeenLastCalledWith(id, representation, 'conditions');
+  });
+
+  it('converts the data if the content-type is not supported.', async(): Promise<void> => {
+    metadata.contentType = 'text/plain';
+    const id = { path: 'identifier' };
+
+    await expect(store.addResource(id, representation, 'conditions' as any)).resolves.toBeUndefined();
+    expect(source.addResource).toHaveBeenLastCalledWith(id, 'converted', 'conditions');
+
+    await expect(store.setRepresentation(id, representation, 'conditions' as any)).resolves.toBeUndefined();
+    expect(source.setRepresentation).toHaveBeenLastCalledWith(id, 'converted', 'conditions');
+  });
+});
diff --git a/test/unit/storage/accessors/SparqlDataAccessor.test.ts b/test/unit/storage/accessors/SparqlDataAccessor.test.ts
index 6aa7807c1..8c471131b 100644
--- a/test/unit/storage/accessors/SparqlDataAccessor.test.ts
+++ b/test/unit/storage/accessors/SparqlDataAccessor.test.ts
@@ -10,6 +10,7 @@ import { UrlContainerManager } from '../../../../src/storage/UrlContainerManager
 import { INTERNAL_QUADS } from '../../../../src/util/ContentTypes';
 import { ConflictHttpError } from '../../../../src/util/errors/ConflictHttpError';
 import { NotFoundHttpError } from '../../../../src/util/errors/NotFoundHttpError';
+import { UnsupportedHttpError } from '../../../../src/util/errors/UnsupportedHttpError';
 import { UnsupportedMediaTypeHttpError } from '../../../../src/util/errors/UnsupportedMediaTypeHttpError';
 import { MetadataController } from '../../../../src/util/MetadataController';
 import { CONTENT_TYPE, LDP, RDF } from '../../../../src/util/UriConstants';
@@ -193,9 +194,15 @@ describe('A SparqlDataAccessor', (): void => {
 
   it('errors when trying to write to a metadata document.', async(): Promise<void> => {
     const data = streamifyArray([ quad(namedNode('http://name'), namedNode('http://pred'), literal('value')) ]);
-    metadata = new RepresentationMetadata('http://test.com/container/resource',
-      { [RDF.type]: [ toNamedNode(LDP.Resource) ]});
     await expect(accessor.writeDocument({ path: 'http://test.com/container/resource.meta' }, data, metadata))
       .rejects.toThrow(new ConflictHttpError('Not allowed to create NamedNodes with the metadata extension.'));
   });
+
+  it('errors when writing triples in a non-default graph.', async(): Promise<void> => {
+    const data = streamifyArray(
+      [ quad(namedNode('http://name'), namedNode('http://pred'), literal('value'), namedNode('badGraph!')) ],
+    );
+    await expect(accessor.writeDocument({ path: 'http://test.com/container/resource' }, data, metadata))
+      .rejects.toThrow(new UnsupportedHttpError('Only triples in the default graph are supported.'));
+  });
 });