diff --git "a/ntoskrnl/mm/ARM3/mdlsup.c" "b/ntoskrnl/mm/ARM3/mdlsup.c"
index 1bd22c1e78a..0d3d124fb7c 100644
--- "a/ntoskrnl/mm/ARM3/mdlsup.c"
+++ "b/ntoskrnl/mm/ARM3/mdlsup.c"
@@ -697,10 +697,17 @@ MmMapLockedPagesSpecifyCache(IN PMDL Mdl,
         //
         // Sanity checks
         //
-        ASSERT((Mdl->MdlFlags & (MDL_MAPPED_TO_SYSTEM_VA |
+        /* For Mdl->MdlFlags == (MDL_MAPPED_TO_SYSTEM_VA | MDL_SOURCE_IS_NONPAGED_POOL)
+         * this exact combination of Flags is used in CORE-17686 for
+         * Regmon Version 4.34 in its regsys.sys Kernel Mode driver
+         * so it should not cause an assert. This is accounted for 
+         * in the two ASSERT's below by their top lines. */
+        ASSERT((Mdl->MdlFlags == (MDL_MAPPED_TO_SYSTEM_VA | MDL_SOURCE_IS_NONPAGED_POOL)) ||
+               (Mdl->MdlFlags & (MDL_MAPPED_TO_SYSTEM_VA |
                                  MDL_SOURCE_IS_NONPAGED_POOL |
                                  MDL_PARTIAL_HAS_BEEN_MAPPED)) == 0);
-        ASSERT((Mdl->MdlFlags & (MDL_PAGES_LOCKED | MDL_PARTIAL)) != 0);
+        ASSERT((Mdl->MdlFlags == (MDL_MAPPED_TO_SYSTEM_VA | MDL_SOURCE_IS_NONPAGED_POOL)) ||
+               (Mdl->MdlFlags & (MDL_PAGES_LOCKED | MDL_PARTIAL)) != 0);
 
         //
         // Get the correct cache type
@@ -786,7 +793,13 @@ MmMapLockedPagesSpecifyCache(IN PMDL Mdl,
         //
         // Mark it as mapped
         //
-        ASSERT((Mdl->MdlFlags & MDL_MAPPED_TO_SYSTEM_VA) == 0);
+        /* For Mdl->MdlFlags == (MDL_MAPPED_TO_SYSTEM_VA | MDL_SOURCE_IS_NONPAGED_POOL)
+         * this exact combination of Flags is used in CORE-17686 for
+         * Regmon Version 4.34 in its regsys.sys Kernel Mode driver
+         * so it should not cause an assert. This is accounted for 
+         * in the ASSERT below by its first line. */
+        ASSERT((Mdl->MdlFlags == (MDL_MAPPED_TO_SYSTEM_VA | MDL_SOURCE_IS_NONPAGED_POOL)) ||
+               (Mdl->MdlFlags & MDL_MAPPED_TO_SYSTEM_VA) == 0);
         Mdl->MappedSystemVa = Base;
         Mdl->MdlFlags |= MDL_MAPPED_TO_SYSTEM_VA;