diff --git a/OvmfPkg/Library/PlatformInitLib/MemDetect.c b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
index acf90b4e93..1102b00ecb 100644
--- a/OvmfPkg/Library/PlatformInitLib/MemDetect.c
+++ b/OvmfPkg/Library/PlatformInitLib/MemDetect.c
@@ -663,6 +663,11 @@ PlatformAddressWidthFromCpuid (
       PhysBits = 40;
     }
 
+    if (!FixedPcdGetBool (PcdUse1GPageTable) && (PhysBits > 40)) {
+      DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 40 (PcdUse1GPageTable is false)\n", __func__));
+      PhysBits = 40;
+    }
+
     PlatformInfoHob->PhysMemAddressWidth = PhysBits;
     PlatformInfoHob->FirstNonAddress     = LShiftU64 (1, PlatformInfoHob->PhysMemAddressWidth);
   }
diff --git a/OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf b/OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf
index 86a82ad3e0..5a79d95b68 100644
--- a/OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf
+++ b/OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf
@@ -58,6 +58,7 @@
 
 [Pcd]
   gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
+  gEfiMdeModulePkgTokenSpaceGuid.PcdUse1GPageTable
 
 [FixedPcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase