diff --git a/ntoskrnl/ex/sysinfo.c b/ntoskrnl/ex/sysinfo.c
index 75e3dd452fd..6c6547bf3b8 100644
--- a/ntoskrnl/ex/sysinfo.c
+++ b/ntoskrnl/ex/sysinfo.c
@@ -664,7 +664,13 @@ QSI_DEF(SystemProcessorInformation)
 #else
     Spi->MaximumProcessors = 0;
 #endif
-    Spi->ProcessorFeatureBits = KeFeatureBits;
+
+    /* According to Geoff Chappell, on Win 8.1 x64 / Win 10 x86, where this
+       field is extended to 64 bits, it continues to produce only the low 32
+       bits. For the full value, use SYSTEM_PROCESSOR_FEATURES_INFORMATION.
+       See https://www.geoffchappell.com/studies/windows/km/ntoskrnl/api/ex/sysinfo/processor.htm
+     */
+    Spi->ProcessorFeatureBits = (ULONG)KeFeatureBits;
 
     DPRINT("Arch %u Level %u Rev 0x%x\n", Spi->ProcessorArchitecture,
         Spi->ProcessorLevel, Spi->ProcessorRevision);
diff --git a/ntoskrnl/include/internal/i386/ke.h b/ntoskrnl/include/internal/i386/ke.h
index 81194e91e0e..596c58b418f 100644
--- a/ntoskrnl/include/internal/i386/ke.h
+++ b/ntoskrnl/include/internal/i386/ke.h
@@ -462,7 +462,7 @@ NTAPI
 KiSetProcessorType(VOID);
 
 CODE_SEG("INIT")
-ULONG
+ULONG64
 NTAPI
 KiGetFeatureBits(VOID);
 
diff --git a/ntoskrnl/include/internal/ke.h b/ntoskrnl/include/internal/ke.h
index c5fcd5b8af3..5af00103476 100644
--- a/ntoskrnl/include/internal/ke.h
+++ b/ntoskrnl/include/internal/ke.h
@@ -103,7 +103,7 @@ extern BOOLEAN ExCmosClockIsSane;
 extern USHORT KeProcessorArchitecture;
 extern USHORT KeProcessorLevel;
 extern USHORT KeProcessorRevision;
-extern ULONG KeFeatureBits;
+extern ULONG64 KeFeatureBits;
 extern KNODE KiNode0;
 extern PKNODE KeNodeBlock[1];
 extern UCHAR KeNumberNodes;
diff --git a/ntoskrnl/ke/amd64/krnlinit.c b/ntoskrnl/ke/amd64/krnlinit.c
index d7aea4db738..f580cacbba9 100644
--- a/ntoskrnl/ke/amd64/krnlinit.c
+++ b/ntoskrnl/ke/amd64/krnlinit.c
@@ -233,7 +233,7 @@ KiInitializeKernel(IN PKPROCESS InitProcess,
     ULONG i;
 
     /* Set boot-level flags */
-    KeFeatureBits = Prcb->FeatureBits;
+    KeFeatureBits = Prcb->FeatureBits | (ULONG64)Prcb->FeatureBitsHigh << 32;
 
     /* Initialize 8/16 bit SList support */
     RtlpUse16ByteSLists = (KeFeatureBits & KF_CMPXCHG16B) ? TRUE : FALSE;
diff --git a/ntoskrnl/ke/i386/cpu.c b/ntoskrnl/ke/i386/cpu.c
index 598a21d9de1..ab639340443 100644
--- a/ntoskrnl/ke/i386/cpu.c
+++ b/ntoskrnl/ke/i386/cpu.c
@@ -209,13 +209,13 @@ KiSetProcessorType(VOID)
 }
 
 CODE_SEG("INIT")
-ULONG
+ULONG64
 NTAPI
 KiGetFeatureBits(VOID)
 {
     PKPRCB Prcb = KeGetCurrentPrcb();
     ULONG Vendor;
-    ULONG FeatureBits = KF_WORKING_PTE;
+    ULONG64 FeatureBits = KF_WORKING_PTE;
     CPU_INFO CpuInfo, DummyCpuInfo;
     UCHAR Ccr1;
     BOOLEAN ExtendedCPUID = TRUE;
diff --git a/ntoskrnl/ke/i386/kiinit.c b/ntoskrnl/ke/i386/kiinit.c
index e3ec9ed94bf..4d576e86f8a 100644
--- a/ntoskrnl/ke/i386/kiinit.c
+++ b/ntoskrnl/ke/i386/kiinit.c
@@ -384,7 +384,7 @@ KiVerifyCpuFeatures(PKPRCB Prcb)
         KeBugCheckEx(UNSUPPORTED_PROCESSOR, 0x386, 0, 0, 0);
 
     // 3. Finally, obtain CPU features.
-    ULONG FeatureBits = KiGetFeatureBits();
+    ULONG64 FeatureBits = KiGetFeatureBits();
 
     // 4. Verify it supports everything we need.
     if (!(FeatureBits & KF_RDTSC))
@@ -423,7 +423,8 @@ KiVerifyCpuFeatures(PKPRCB Prcb)
     }
 
     // 5. Save feature bits.
-    Prcb->FeatureBits = FeatureBits;
+    Prcb->FeatureBits = (ULONG)FeatureBits;
+    Prcb->FeatureBitsHigh = FeatureBits >> 32;
 }
 
 CODE_SEG("INIT")
@@ -445,7 +446,7 @@ KiInitializeKernel(IN PKPROCESS InitProcess,
 
     /* Set boot-level flags */
     if (Number == 0)
-        KeFeatureBits = Prcb->FeatureBits;
+        KeFeatureBits = Prcb->FeatureBits | (ULONG64)Prcb->FeatureBitsHigh << 32;
 
     /* Set the default NX policy (opt-in) */
     SharedUserData->NXSupportPolicy = NX_SUPPORT_POLICY_OPTIN;
diff --git a/ntoskrnl/ke/krnlinit.c b/ntoskrnl/ke/krnlinit.c
index 4ffdb0bd104..edb455abfc5 100644
--- a/ntoskrnl/ke/krnlinit.c
+++ b/ntoskrnl/ke/krnlinit.c
@@ -19,7 +19,7 @@
 USHORT KeProcessorArchitecture;
 USHORT KeProcessorLevel;
 USHORT KeProcessorRevision;
-ULONG KeFeatureBits;
+ULONG64 KeFeatureBits;
 
 /* System call count */
 ULONG KiServiceLimit = NUMBER_OF_SYSCALLS;
diff --git a/sdk/include/ndk/amd64/ketypes.h b/sdk/include/ndk/amd64/ketypes.h
index 08c94196db3..5d65d4a3508 100644
--- a/sdk/include/ndk/amd64/ketypes.h
+++ b/sdk/include/ndk/amd64/ketypes.h
@@ -939,8 +939,11 @@ typedef struct _KPRCB
     ULONG CacheCount;
 #endif
 #ifdef __REACTOS__
+#if  (NTDDI_VERSION < NTDDI_WINBLUE)
+    // On Win 8.1+ the FeatureBits field is extended to 64 bits
     ULONG FeatureBitsHigh;
 #endif
+#endif
 } KPRCB, *PKPRCB;
 
 //
diff --git a/sdk/include/ndk/extypes.h b/sdk/include/ndk/extypes.h
index 2b190f1ca30..251a7a0e6f2 100644
--- a/sdk/include/ndk/extypes.h
+++ b/sdk/include/ndk/extypes.h
@@ -761,7 +761,11 @@ typedef struct _SYSTEM_PROCESSOR_INFORMATION
 #else
     USHORT MaximumProcessors;
 #endif
+#if (NTDDI_VERSION >= NTDDI_WIN10) || ((NTDDI_VERSION >= NTDDI_WINBLUE) && defined(_WIN64))
+    ULONG64 ProcessorFeatureBits;
+#else
     ULONG ProcessorFeatureBits;
+#endif
 } SYSTEM_PROCESSOR_INFORMATION, *PSYSTEM_PROCESSOR_INFORMATION;
 
 // Class 2
diff --git a/sdk/include/ndk/i386/ketypes.h b/sdk/include/ndk/i386/ketypes.h
index 757fd4e82d4..e97f243b6c0 100644
--- a/sdk/include/ndk/i386/ketypes.h
+++ b/sdk/include/ndk/i386/ketypes.h
@@ -781,6 +781,12 @@ typedef struct _KPRCB
     ULONG PackageProcessorSet;
     ULONG CoreProcessorSet;
 #endif
+#ifdef __REACTOS__
+#if  (NTDDI_VERSION < NTDDI_WIN10)
+    // On Win 10+ the FeatureBits field is extended to 64 bits
+    ULONG FeatureBitsHigh;
+#endif
+#endif
 } KPRCB, *PKPRCB;
 
 //