diff --git a/src/main/java/net/schmizz/sshj/transport/verification/OpenSSHKnownHosts.java b/src/main/java/net/schmizz/sshj/transport/verification/OpenSSHKnownHosts.java
index 670d41cfc..b04f95932 100644
--- a/src/main/java/net/schmizz/sshj/transport/verification/OpenSSHKnownHosts.java
+++ b/src/main/java/net/schmizz/sshj/transport/verification/OpenSSHKnownHosts.java
@@ -387,7 +387,7 @@ public String getLine() {
             line.append(" ").append(type.toString());
             line.append(" ").append(getKeyString(key));
 
-            if (!comment.isEmpty()) line.append(" ").append(comment);
+            if (comment != null && !comment.isEmpty()) line.append(" ").append(comment);
 
             return line.toString();
         }