diff --git a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java
index 04d823d1..07098269 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/decryption_verification/OpenPgpMessageInputStream.java
@@ -544,6 +544,7 @@ public class OpenPgpMessageInputStream extends DecryptionStream {
             for (Tuple<PGPSecretKey, PGPPublicKeyEncryptedData> k : postponedDueToMissingPassphrase) {
                 PGPSecretKey key = k.getA();
                 PGPSecretKeyRing keys = getDecryptionKey(key.getKeyID());
+                assert (keys != null);
                 keyIds.add(new SubkeyIdentifier(keys, key.getKeyID()));
             }
             if (!keyIds.isEmpty()) {
@@ -556,6 +557,7 @@ public class OpenPgpMessageInputStream extends DecryptionStream {
                     PGPSecretKey secretKey = missingPassphrases.getA();
                     long keyId = secretKey.getKeyID();
                     PGPSecretKeyRing decryptionKey = getDecryptionKey(keyId);
+                    assert (decryptionKey != null);
                     SubkeyIdentifier decryptionKeyId = new SubkeyIdentifier(decryptionKey, keyId);
                     if (hasUnsupportedS2KSpecifier(secretKey, decryptionKeyId)) {
                         continue;
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/certification/CertifyCertificate.java b/pgpainless-core/src/main/java/org/pgpainless/key/certification/CertifyCertificate.java
index 05e64879..9340d93d 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/certification/CertifyCertificate.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/certification/CertifyCertificate.java
@@ -275,6 +275,7 @@ public class CertifyCertificate {
         // We only support certification-capable primary keys
         OpenPgpFingerprint fingerprint = info.getFingerprint();
         PGPPublicKey certificationPubKey = info.getPublicKey(fingerprint);
+        assert (certificationPubKey != null);
         if (!info.isKeyValidlyBound(certificationPubKey.getKeyID())) {
             throw new KeyException.RevokedKeyException(fingerprint);
         }
diff --git a/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java b/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java
index 6210ef5b..73c39c25 100644
--- a/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java
+++ b/pgpainless-core/src/main/java/org/pgpainless/key/modification/secretkeyring/SecretKeyRingEditor.java
@@ -182,7 +182,10 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
             }
 
             // We need to unmark this user-id as primary
-            if (info.getLatestUserIdCertification(otherUserId).getHashedSubPackets().isPrimaryUserID()) {
+            PGPSignature userIdCertification = info.getLatestUserIdCertification(otherUserId);
+            assert (userIdCertification != null);
+
+            if (userIdCertification.getHashedSubPackets().isPrimaryUserID()) {
                 addUserId(otherUserId, new SelfSignatureSubpackets.Callback() {
                     @Override
                     public void modifyHashedSubpackets(SelfSignatureSubpackets hashedSubpackets) {
@@ -601,6 +604,7 @@ public class SecretKeyRingEditor implements SecretKeyRingEditorInterface {
             }
 
             if (prevUserIdSig.getHashedSubPackets().isPrimaryUserID()) {
+                assert (primaryUserId != null);
                 PGPSignature userIdSig = reissueNonPrimaryUserId(secretKeyRingProtector, userId, prevUserIdSig);
                 secretKeyRing = KeyRingUtils.injectCertification(secretKeyRing, primaryUserId, userIdSig);
             }