diff --git a/reactos/subsystems/mvdm/ntvdm/bios/umamgr.c b/reactos/subsystems/mvdm/ntvdm/bios/umamgr.c
index 258b9eafa38..9f236932c9e 100644
--- a/reactos/subsystems/mvdm/ntvdm/bios/umamgr.c
+++ b/reactos/subsystems/mvdm/ntvdm/bios/umamgr.c
@@ -91,11 +91,11 @@ BOOLEAN UmaDescReserve(IN OUT PUSHORT Segment, IN OUT PUSHORT Size)
     // FIXME: Check! What to do?
     if (RequestSize == 0) DPRINT1("Requesting UMA descriptor with null size?!\n");
 
-    for (Entry = UmaDescriptorList.Flink;
-         Entry != &UmaDescriptorList;
-         Entry = Entry->Flink)
+    Entry = UmaDescriptorList.Flink;
+    while (Entry != &UmaDescriptorList)
     {
         UmaDesc = (PUMA_DESCRIPTOR)CONTAINING_RECORD(Entry, UMA_DESCRIPTOR, Entry);
+        Entry = Entry->Flink;
 
         /* Only check free descriptors */
         if (UmaDesc->Type != UMA_FREE) continue;
@@ -209,11 +209,11 @@ BOOLEAN UmaDescRelease(IN USHORT Segment)
     PUMA_DESCRIPTOR UmaDesc, PrevDesc = NULL, NextDesc = NULL;
     PUMA_DESCRIPTOR FoundUmaDesc = NULL;
 
-    for (Entry = UmaDescriptorList.Flink;
-         Entry != &UmaDescriptorList;
-         Entry = Entry->Flink)
+    Entry = UmaDescriptorList.Flink;
+    while (Entry != &UmaDescriptorList)
     {
         UmaDesc = (PUMA_DESCRIPTOR)CONTAINING_RECORD(Entry, UMA_DESCRIPTOR, Entry);
+        Entry = Entry->Flink;
 
         /* Search for the descriptor in the list */
         if (UmaDesc->Start == Address && UmaDesc->Type == UMA_UMB)
@@ -267,11 +267,11 @@ BOOLEAN UmaDescReallocate(IN USHORT Segment, IN OUT PUSHORT Size)
     // FIXME: Check! What to do?
     if (RequestSize == 0) DPRINT1("Resizing UMA descriptor %04X to null size?!\n", Segment);
 
-    for (Entry = UmaDescriptorList.Flink;
-         Entry != &UmaDescriptorList;
-         Entry = Entry->Flink)
+    Entry = UmaDescriptorList.Flink;
+    while (Entry != &UmaDescriptorList)
     {
         UmaDesc = (PUMA_DESCRIPTOR)CONTAINING_RECORD(Entry, UMA_DESCRIPTOR, Entry);
+        Entry = Entry->Flink;
 
         /* Only get the maximum size of free descriptors */
         if (UmaDesc->Type == UMA_FREE)
diff --git a/reactos/subsystems/mvdm/ntvdm/clock.c b/reactos/subsystems/mvdm/ntvdm/clock.c
index 0250ea8bac8..54096dfa92f 100644
--- a/reactos/subsystems/mvdm/ntvdm/clock.c
+++ b/reactos/subsystems/mvdm/ntvdm/clock.c
@@ -65,6 +65,7 @@ VOID ClockUpdate(VOID)
     extern BOOLEAN CpuRunning;
     UINT i;
     PLIST_ENTRY Entry;
+    PHARDWARE_TIMER Timer;
 
     while (VdmRunning && CpuRunning)
     {
@@ -81,10 +82,13 @@ VOID ClockUpdate(VOID)
             ++Cycles;
         }
 
-        for (Entry = Timers.Flink; Entry != &Timers; Entry = Entry->Flink)
+        Entry = Timers.Flink;
+        while (Entry != &Timers)
         {
             ULONGLONG Ticks = (ULONGLONG)-1;
-            PHARDWARE_TIMER Timer = CONTAINING_RECORD(Entry, HARDWARE_TIMER, Link);
+
+            Timer = CONTAINING_RECORD(Entry, HARDWARE_TIMER, Link);
+            Entry = Entry->Flink;
 
             ASSERT((Timer->EnableCount > 0) && (Timer->Flags & HARDWARE_TIMER_ENABLED));
 
@@ -128,12 +132,13 @@ PHARDWARE_TIMER CreateHardwareTimer(ULONG Flags, ULONGLONG Delay, PHARDWARE_TIME
 {
     PHARDWARE_TIMER Timer;
 
-    Timer = RtlAllocateHeap(RtlGetProcessHeap(), 0, sizeof(*Timer));
+    Timer = RtlAllocateHeap(RtlGetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*Timer));
     if (Timer == NULL) return NULL;
 
     Timer->Flags = Flags & ~HARDWARE_TIMER_ENABLED;
     Timer->EnableCount = 0;
     Timer->Callback = Callback;
+    Timer->LastTick.QuadPart = 0;
     SetHardwareTimerDelay(Timer, Delay);
 
     if (Flags & HARDWARE_TIMER_ENABLED) EnableHardwareTimer(Timer);
diff --git a/reactos/subsystems/mvdm/ntvdm/clock.h b/reactos/subsystems/mvdm/ntvdm/clock.h
index bc0c3bd5d68..9584628b688 100644
--- a/reactos/subsystems/mvdm/ntvdm/clock.h
+++ b/reactos/subsystems/mvdm/ntvdm/clock.h
@@ -27,8 +27,8 @@ typedef struct _HARDWARE_TIMER
     ULONG Flags;
     LONG EnableCount;
     ULONGLONG Delay;
-    PHARDWARE_TIMER_PROC Callback;
     LARGE_INTEGER LastTick;
+    PHARDWARE_TIMER_PROC Callback;
 } HARDWARE_TIMER, *PHARDWARE_TIMER;
 
 /* FUNCTIONS ******************************************************************/