diff --git a/src/main/java/org/jabref/logic/pdf/search/indexing/PdfIndexer.java b/src/main/java/org/jabref/logic/pdf/search/indexing/PdfIndexer.java
index a28784cb73b..2c0d2cf605e 100644
--- a/src/main/java/org/jabref/logic/pdf/search/indexing/PdfIndexer.java
+++ b/src/main/java/org/jabref/logic/pdf/search/indexing/PdfIndexer.java
@@ -11,6 +11,7 @@
 import javafx.collections.ObservableList;
 
 import org.jabref.gui.LibraryTab;
+import org.jabref.logic.util.StandardFileType;
 import org.jabref.model.database.BibDatabase;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
@@ -188,6 +189,9 @@ private void writeToIndex(BibEntry entry) {
      * @param linkedFile the file to write to the index
      */
     private void writeToIndex(BibEntry entry, LinkedFile linkedFile) {
+        if (linkedFile.isOnlineLink() || !StandardFileType.PDF.getName().equals(linkedFile.getFileType())) {
+            return;
+        }
         Optional<Path> resolvedPath = linkedFile.findIn(databaseContext, filePreferences);
         if (resolvedPath.isEmpty()) {
             LOGGER.warn("Could not find {}", linkedFile.getLink());
diff --git a/src/test/java/org/jabref/logic/pdf/search/indexing/PdfIndexerTest.java b/src/test/java/org/jabref/logic/pdf/search/indexing/PdfIndexerTest.java
index 9dc45525ac8..82f220df784 100644
--- a/src/test/java/org/jabref/logic/pdf/search/indexing/PdfIndexerTest.java
+++ b/src/test/java/org/jabref/logic/pdf/search/indexing/PdfIndexerTest.java
@@ -60,6 +60,38 @@ public void exampleThesisIndex() throws IOException {
         }
     }
 
+    @Test
+    public void dontIndexNonPdf() throws IOException {
+        // given
+        BibEntry entry = new BibEntry(StandardEntryType.PhdThesis);
+        entry.setFiles(Collections.singletonList(new LinkedFile("Example Thesis", "thesis-example.pdf", StandardFileType.AUX.getName())));
+        database.insertEntry(entry);
+
+        // when
+        indexer.createIndex(database, context);
+
+        // then
+        try (IndexReader reader = DirectoryReader.open(new NIOFSDirectory(context.getFulltextIndexPath()))) {
+            assertEquals(0, reader.numDocs());
+        }
+    }
+
+    @Test
+    public void dontIndexOnlineLinks() throws IOException {
+        // given
+        BibEntry entry = new BibEntry(StandardEntryType.PhdThesis);
+        entry.setFiles(Collections.singletonList(new LinkedFile("Example Thesis", "https://raw.githubusercontent.com/JabRef/jabref/main/src/test/resources/pdfs/thesis-example.pdf", StandardFileType.PDF.getName())));
+        database.insertEntry(entry);
+
+        // when
+        indexer.createIndex(database, context);
+
+        // then
+        try (IndexReader reader = DirectoryReader.open(new NIOFSDirectory(context.getFulltextIndexPath()))) {
+            assertEquals(0, reader.numDocs());
+        }
+    }
+
     @Test
     public void exampleThesisIndexWithKey() throws IOException {
         // given