diff --git a/lang/cpp/src/key.cpp b/lang/cpp/src/key.cpp
index 31e59e19..66fdea96 100644
--- a/lang/cpp/src/key.cpp
+++ b/lang/cpp/src/key.cpp
@@ -236,7 +236,18 @@ bool Key::isQualified() const
 
 bool Key::isDeVs() const
 {
-    return key && key->subkeys && key->subkeys->is_de_vs;
+    if (!key) {
+        return false;
+    }
+    if (!key->subkeys || !key->subkeys->is_de_vs) {
+        return false;
+    }
+    for (gpgme_sub_key_t subkey = key->subkeys ; subkey ; subkey = subkey->next) {
+        if (!subkey->is_de_vs) {
+            return false;
+        }
+    }
+    return true;
 }
 
 const char *Key::issuerSerial() const