Index: /trunk/src/VBox/VMM/VMMAll/GIMAllHv.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMAll/GIMAllHv.cpp	(revision 58249)
+++ /trunk/src/VBox/VMM/VMMAll/GIMAllHv.cpp	(revision 58250)
@@ -729,5 +729,5 @@
                 LogRelMax(1, ("GIM: HyperV: Guest initiated debug data transmission via MSR\n",
                               MSR_GIM_HV_SYNTH_DEBUG_CONTROL_W_LEN(uRawValue)));
-                size_t cbWrite = MSR_GIM_HV_SYNTH_DEBUG_CONTROL_W_LEN(uRawValue);
+                uint32_t cbWrite = MSR_GIM_HV_SYNTH_DEBUG_CONTROL_W_LEN(uRawValue);
                 if (   cbWrite > 0
                     && cbWrite < GIM_HV_PAGE_SIZE)