diff --git a/src/kcrash.cpp b/src/kcrash.cpp
--- a/src/kcrash.cpp
+++ b/src/kcrash.cpp
@@ -561,10 +561,15 @@
         }
 
         // make sure the constData() pointer remains valid when we call startProcess by making a copy
-        QByteArray startupId = KStartupInfo::startupId();
-        if (!startupId.isNull()) {
+        char startupId[128];
+        if (!KStartupInfo::startupId().isNull()) {
+            // null-terminate it
+            std::copy_n(KStartupInfo::startupId().constBegin(), std::min(sizeof(startupId)-1, (unsigned)KStartupInfo::startupId().size()), startupId) [0] = 0;
+            if (sizeof(startupId)-1 < KStartupInfo::startupId().size())
+                fprintf (stderr, "KCrash: startupId buffer not big enough\n");
+
             argv[i++] = "--startupid";
-            argv[i++] = startupId.constData();
+            argv[i++] = startupId;
         }
 
         if (s_flags & SaferDialog) {