diff --git a/sortix/kernel.cpp b/sortix/kernel.cpp
index 7fa8d90d..8e6258c9 100644
--- a/sortix/kernel.cpp
+++ b/sortix/kernel.cpp
@@ -226,7 +226,7 @@ namespace Sortix
 		// Initialize the scheduler.
 		Scheduler::Init();
 
-		Thread::Entry initstart = RunApplication;
+		Thread::Entry initstart = NULL;
 
 		// Create an address space for the first process.
 		addr_t addrspace = Memory::Fork();
diff --git a/sortix/memorymanagement.h b/sortix/memorymanagement.h
index 986e0dd0..460d3ba9 100644
--- a/sortix/memorymanagement.h
+++ b/sortix/memorymanagement.h
@@ -60,7 +60,7 @@ namespace Sortix
 
 #if defined(PLATFORM_X86)
 		const addr_t HEAPLOWER = 0x80000000UL;
-		const addr_t HEAPUPPER = 0xFF800000UL;
+		const addr_t HEAPUPPER = 0xFF400000UL;
 #elif defined(PLATFORM_X64)
 		const addr_t HEAPLOWER = 0xFFFF800000000000UL;
 		const addr_t HEAPUPPER = 0xFFFFFE8000000000UL;
diff --git a/sortix/x86-family/memorymanagement.cpp b/sortix/x86-family/memorymanagement.cpp
index b72db72f..e0a4b7d9 100644
--- a/sortix/x86-family/memorymanagement.cpp
+++ b/sortix/x86-family/memorymanagement.cpp
@@ -129,6 +129,11 @@ namespace Sortix
 				if ( !page ) { Panic("out of memory allocating boot PMLs"); }
 
 				pml->entry[i] = page | flags;
+
+				// Invalidate the new PML and reset it to zeroes.
+				addr_t pmladdr = (addr_t) (PMLS[TOPPMLLEVEL-1] + i);
+				InvalidatePage(pmladdr);
+				Maxsi::Memory::Set((void*) pmladdr, 0, sizeof(PML));
 			}
 		}
 	}
@@ -318,8 +323,8 @@ namespace Sortix
 				else if ( userspace && !(entry & PML_USERSPACE) )
 				{
 					PanicF("attempted to map physical page %p to virtual page "
-					       "%p with userspace permissions, but the virtual page"
-					       "wasn't in an userspace PML[%zu]. This is a bug in the"
+					       "%p with userspace permissions, but the virtual page "
+					       "wasn't in an userspace PML[%zu]. This is a bug in the "
 					       "code calling this function", physical, mapto, i-1);
 				}
 
@@ -362,8 +367,8 @@ namespace Sortix
 				}
 				else if ( userspace && !(entry & PML_USERSPACE) )
 				{
-					PanicF("attempted to unmap virtual page %p it wasn't in an"
-					       "userspace PML[%zu]. This is a bug in the code"
+					PanicF("attempted to unmap virtual page %p it wasn't in an "
+					       "userspace PML[%zu]. This is a bug in the code "
 					       "calling this function", mapto, i-1);
 				}
 
@@ -437,7 +442,7 @@ namespace Sortix
 				addr_t entry = (PMLS[level] + pmloffset)->entry[pos];
 
 				// If the entry should be forked, fork it!
-				if ( likely(entry & PML_FORK) )
+				if ( (entry & PML_FORK) && (entry & PML_PRESENT) )
 				{
 					// Pop the physical address of somewhere unused.
 					addr_t phys = Page::Get();
diff --git a/sortix/x86/memorymanagement.cpp b/sortix/x86/memorymanagement.cpp
index fc78619d..1ff2f40a 100644
--- a/sortix/x86/memorymanagement.cpp
+++ b/sortix/x86/memorymanagement.cpp
@@ -49,7 +49,7 @@ namespace Sortix
 			PML* const IDENPML1 = (PML* const) 0x04000UL;
 
 			// Initialize the memory structures with zeroes.
-			Maxsi::Memory::Set(BOOTPML1, 0, 0x6000UL);
+			Maxsi::Memory::Set((PML* const) 0x01000UL, 0, 0x6000UL);
 
 			// Identity map the first 4 MiB.
 			addr_t flags = PML_PRESENT | PML_WRITABLE;