diff --git a/arduino/libraries/librariesmanager/download.go b/arduino/libraries/librariesmanager/download.go
index b3920fca756..254f88a981d 100644
--- a/arduino/libraries/librariesmanager/download.go
+++ b/arduino/libraries/librariesmanager/download.go
@@ -27,3 +27,6 @@ var LibraryIndexGZURL, _ = url.Parse("https://downloads.arduino.cc/libraries/lib
 
 // LibraryIndexSignature is the URL where to get the library index signature.
 var LibraryIndexSignature, _ = url.Parse("https://downloads.arduino.cc/libraries/library_index.json.sig")
+
+// LibraryIndexWithSignatureArchiveURL is the URL where to get the library index.
+var LibraryIndexWithSignatureArchiveURL, _ = url.Parse("https://downloads.arduino.cc/libraries/library_index.tar.bz2")
diff --git a/commands/instances.go b/commands/instances.go
index d6bd76ae7d9..0840bca5cd7 100644
--- a/commands/instances.go
+++ b/commands/instances.go
@@ -479,8 +479,7 @@ func UpdateLibrariesIndex(ctx context.Context, req *rpc.UpdateLibrariesIndexRequ
 	defer tmp.RemoveAll()
 
 	indexResource := resources.IndexResource{
-		URL:          librariesmanager.LibraryIndexGZURL,
-		SignatureURL: librariesmanager.LibraryIndexSignature,
+		URL: librariesmanager.LibraryIndexWithSignatureArchiveURL,
 	}
 	if err := indexResource.Download(lm.IndexFile.Parent(), downloadCB); err != nil {
 		return err
diff --git a/test/test_lib.py b/test/test_lib.py
index 71867e2044d..bdbaef9eb4d 100644
--- a/test/test_lib.py
+++ b/test/test_lib.py
@@ -447,8 +447,7 @@ def test_update_index(run_command):
     result = run_command(["lib", "update-index"])
     assert result.ok
     lines = [l.strip() for l in result.stdout.splitlines()]
-    assert "Downloading index: library_index.json.gz downloaded" in lines
-    assert "Downloading index signature: library_index.json.sig downloaded" in lines
+    assert "Downloading index: library_index.tar.bz2 downloaded" in lines
 
 
 def test_uninstall(run_command):
@@ -498,8 +497,7 @@ def test_search(run_command):
     result = run_command(["lib", "search", "--names"])
     assert result.ok
     lines = [l.strip() for l in result.stdout.strip().splitlines()]
-    assert "Downloading index: library_index.json.gz downloaded" in lines
-    assert "Downloading index signature: library_index.json.sig downloaded" in lines
+    assert "Downloading index: library_index.tar.bz2 downloaded" in lines
     libs = [l[6:].strip('"') for l in lines if "Name:" in l]
 
     expected = {"WiFi101", "WiFi101OTA", "Firebase Arduino based on WiFi101"}
diff --git a/test/test_update.py b/test/test_update.py
index 54f804f3189..f944347c071 100644
--- a/test/test_update.py
+++ b/test/test_update.py
@@ -22,8 +22,7 @@ def test_update(run_command):
     lines = [l.strip() for l in res.stdout.splitlines()]
 
     assert "Downloading index: package_index.tar.bz2 downloaded" in lines
-    assert "Downloading index: library_index.json.gz downloaded" in lines
-    assert "Downloading index signature: library_index.json.sig downloaded" in lines
+    assert "Downloading index: library_index.tar.bz2 downloaded" in lines
 
 
 def test_update_showing_outdated(run_command):
@@ -45,8 +44,7 @@ def test_update_showing_outdated(run_command):
     lines = [l.strip() for l in result.stdout.splitlines()]
 
     assert "Downloading index: package_index.tar.bz2 downloaded" in lines
-    assert "Downloading index: library_index.json.gz downloaded" in lines
-    assert "Downloading index signature: library_index.json.sig downloaded" in lines
+    assert "Downloading index: library_index.tar.bz2 downloaded" in lines
     assert lines[-5].startswith("Arduino AVR Boards")
     assert lines[-2].startswith("USBHost")