diff --git a/pgpainless-cli/src/test/java/org/pgpainless/cli/commands/VersionCmdTest.java b/pgpainless-cli/src/test/java/org/pgpainless/cli/commands/VersionCmdTest.java
index 2e4aa7e4..87f535a8 100644
--- a/pgpainless-cli/src/test/java/org/pgpainless/cli/commands/VersionCmdTest.java
+++ b/pgpainless-cli/src/test/java/org/pgpainless/cli/commands/VersionCmdTest.java
@@ -41,4 +41,12 @@ public class VersionCmdTest extends CLITest {
         assertTrue(info.contains("Bouncy Castle"));
         assertTrue(info.contains("Stateless OpenPGP Protocol"));
     }
+
+    @Test
+    public void testSopSpecVersion() throws IOException {
+        ByteArrayOutputStream out = pipeStdoutToStream();
+        assertSuccess(executeCommand("version", "--sop-spec"));
+        String info = out.toString();
+        assertTrue(info.startsWith("draft-dkg-openpgp-stateless-cli-"));
+    }
 }
diff --git a/pgpainless-sop/src/main/java/org/pgpainless/sop/VersionImpl.java b/pgpainless-sop/src/main/java/org/pgpainless/sop/VersionImpl.java
index 8986e295..82995edf 100644
--- a/pgpainless-sop/src/main/java/org/pgpainless/sop/VersionImpl.java
+++ b/pgpainless-sop/src/main/java/org/pgpainless/sop/VersionImpl.java
@@ -18,7 +18,7 @@ import sop.operation.Version;
 public class VersionImpl implements Version {
 
     // draft version
-    private static final String SOP_VERSION = "06";
+    private static final int SOP_VERSION = 6;
 
     @Override
     public String getName() {
@@ -51,11 +51,12 @@ public class VersionImpl implements Version {
 
     @Override
     public String getExtendedVersion() {
+        String FORMAT_VERSION = String.format("%02d", SOP_VERSION);
         return getName() + " " + getVersion() + "\n" +
                 "https://codeberg.org/PGPainless/pgpainless/src/branch/master/pgpainless-sop\n" +
                 "\n" +
-                "Implementation of the Stateless OpenPGP Protocol Version " + SOP_VERSION + "\n" +
-                "https://datatracker.ietf.org/doc/html/draft-dkg-openpgp-stateless-cli-" + SOP_VERSION + "\n" +
+                "Implementation of the Stateless OpenPGP Protocol Version " + FORMAT_VERSION + "\n" +
+                "https://datatracker.ietf.org/doc/html/draft-dkg-openpgp-stateless-cli-" + FORMAT_VERSION + "\n" +
                 "\n" +
                 "Based on pgpainless-core " + getVersion() + "\n" +
                 "https://pgpainless.org\n" +
@@ -65,7 +66,17 @@ public class VersionImpl implements Version {
     }
 
     @Override
-    public String getSopSpecVersion() {
-        return "draft-dkg-openpgp-stateless-cli-" + SOP_VERSION;
+    public int getSopSpecVersionNumber() {
+        return SOP_VERSION;
+    }
+
+    @Override
+    public boolean isSopSpecImplementationIncomplete() {
+        return false;
+    }
+
+    @Override
+    public String getSopSpecImplementationIncompletenessRemarks() {
+        return null;
     }
 }
diff --git a/pgpainless-sop/src/test/java/org/pgpainless/sop/VersionTest.java b/pgpainless-sop/src/test/java/org/pgpainless/sop/VersionTest.java
index c9739471..fa4af6a8 100644
--- a/pgpainless-sop/src/test/java/org/pgpainless/sop/VersionTest.java
+++ b/pgpainless-sop/src/test/java/org/pgpainless/sop/VersionTest.java
@@ -7,6 +7,7 @@ package org.pgpainless.sop;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
@@ -49,4 +50,26 @@ public class VersionTest {
         String firstLine = extendedVersion.split("\n")[0];
         assertEquals(sop.version().getName() + " " + sop.version().getVersion(), firstLine);
     }
+
+    @Test
+    public void testGetSopSpecVersion() {
+        boolean incomplete = sop.version().isSopSpecImplementationIncomplete();
+        int revisionNumber = sop.version().getSopSpecVersionNumber();
+
+        String revisionString = sop.version().getSopSpecRevisionString();
+        assertEquals("draft-dkg-openpgp-stateless-cli-" + String.format("%02d", revisionNumber), revisionString);
+
+        String incompletenessRemarks = sop.version().getSopSpecImplementationIncompletenessRemarks();
+
+        String fullSopSpecVersion = sop.version().getSopSpecVersion();
+        if (incomplete) {
+            assertTrue(fullSopSpecVersion.startsWith("~" + revisionString));
+        } else {
+            assertTrue(fullSopSpecVersion.startsWith(revisionString));
+        }
+
+        if (incompletenessRemarks != null) {
+            assertTrue(fullSopSpecVersion.endsWith(incompletenessRemarks));
+        }
+    }
 }