Index: /trunk/src/VBox/Additions/WINNT/Graphics/Video/mp/wddm/VBoxMPWddm.cpp
===================================================================
--- /trunk/src/VBox/Additions/WINNT/Graphics/Video/mp/wddm/VBoxMPWddm.cpp	(revision 66538)
+++ /trunk/src/VBox/Additions/WINNT/Graphics/Video/mp/wddm/VBoxMPWddm.cpp	(revision 66539)
@@ -5006,9 +5006,11 @@
                     PVBOXDISPIFESCAPE_DBGPRINT pDbgPrint = (PVBOXDISPIFESCAPE_DBGPRINT)pEscapeHdr;
                     /* ensure the last char is \0*/
-                    *((uint8_t*)pDbgPrint + pEscape->PrivateDriverDataSize - 1) = '\0';
-                    if (g_VBoxLogUm & VBOXWDDM_CFG_LOG_UM_DBGPRINT)
-                        DbgPrint("%s\n", pDbgPrint->aStringBuf);
-                    if (g_VBoxLogUm & VBOXWDDM_CFG_LOG_UM_BACKDOOR)
-                        LOGREL_EXACT(("%s\n", pDbgPrint->aStringBuf));
+                    if (*((uint8_t*)pDbgPrint + pEscape->PrivateDriverDataSize - 1) == '\0')
+                    {
+                        if (g_VBoxLogUm & VBOXWDDM_CFG_LOG_UM_DBGPRINT)
+                            DbgPrint("%s\n", pDbgPrint->aStringBuf);
+                        if (g_VBoxLogUm & VBOXWDDM_CFG_LOG_UM_BACKDOOR)
+                            LOGREL_EXACT(("%s\n", pDbgPrint->aStringBuf));
+                    }
                 }
                 Status = STATUS_SUCCESS;