diff --git a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java
new file mode 100644
index 0000000..a5fa2b4
--- /dev/null
+++ b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/ByteStringTest.java
@@ -0,0 +1,70 @@
+package eu.mulk.jgvariant.ostree;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+class ByteStringTest {
+
+  @Test
+  void testToModifiedBase64() {
+    assertEquals("MciDXVydLGaHpQCRyFFC0bLYU_9Bap+4G07jB1RRDVI", testByteString1.modifiedBase64());
+  }
+
+  @Test
+  void testOfModifiedBase64() {
+    assertEquals(
+        testByteString1,
+        ByteString.ofModifiedBase64("MciDXVydLGaHpQCRyFFC0bLYU_9Bap+4G07jB1RRDVI"));
+  }
+
+  @Test
+  void testToHex() {
+    assertEquals(
+        "31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52", testByteString1.hex());
+  }
+
+  @Test
+  void testOfHex() {
+    assertEquals(
+        testByteString1,
+        ByteString.ofHex("31c8835d5c9d2c6687a50091c85142d1b2d853ff416a9fb81b4ee30754510d52"));
+  }
+
+  private static final ByteString testByteString1 =
+      new ByteString(
+          new byte[] {
+            (byte) 0x31,
+            (byte) 0xc8,
+            (byte) 0x83,
+            (byte) 0x5d,
+            (byte) 0x5c,
+            (byte) 0x9d,
+            (byte) 0x2c,
+            (byte) 0x66,
+            (byte) 0x87,
+            (byte) 0xa5,
+            (byte) 0x00,
+            (byte) 0x91,
+            (byte) 0xc8,
+            (byte) 0x51,
+            (byte) 0x42,
+            (byte) 0xd1,
+            (byte) 0xb2,
+            (byte) 0xd8,
+            (byte) 0x53,
+            (byte) 0xff,
+            (byte) 0x41,
+            (byte) 0x6a,
+            (byte) 0x9f,
+            (byte) 0xb8,
+            (byte) 0x1b,
+            (byte) 0x4e,
+            (byte) 0xe3,
+            (byte) 0x07,
+            (byte) 0x54,
+            (byte) 0x51,
+            (byte) 0x0d,
+            (byte) 0x52
+          });
+}
diff --git a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java
index db222f9..031b1cd 100644
--- a/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java
+++ b/jgvariant-ostree/src/test/java/eu/mulk/jgvariant/ostree/OstreeDecoderTest.java
@@ -2,7 +2,6 @@
 
 import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.adelean.inject.resources.junit.jupiter.GivenBinaryResource;
 import com.adelean.inject.resources.junit.jupiter.TestWithResources;
@@ -38,11 +37,6 @@
   byte[] deltaPartPayloadBytes;
 
   @Test
-  void testTrivial() {
-    assertTrue(true);
-  }
-
-  @Test
   void testSummaryDecoder() {
     var decoder = Summary.decoder();
     var summary = decoder.decode(ByteBuffer.wrap(summaryBytes));