6 files changed, 23 insertions, 11 deletions
diff --git a/src/libSystem/SystemKit/Err.h b/src/libSystem/SystemKit/Err.h
index ea36abde..7e8dbee4 100644
--- a/src/libSystem/SystemKit/Err.h
+++ b/src/libSystem/SystemKit/Err.h
@@ -4,7 +4,8 @@
 
 ======================================== */
 
-#pragma once
+#ifndef SYSTEMKIT_ERR_H
+#define SYSTEMKIT_ERR_H
 
 #include <libSystem/SystemKit/Macros.h>
 
@@ -56,3 +57,5 @@ inline constexpr ErrRef kErrorUnimplemented      = -1;
 
 /// @brief The last error reported by the system to the process.
 IMPORT_C ErrRef kLastError;
+
+#endif
diff --git a/src/libSystem/SystemKit/Jail.h b/src/libSystem/SystemKit/Jail.h
index f28968b4..acf392b4 100644
--- a/src/libSystem/SystemKit/Jail.h
+++ b/src/libSystem/SystemKit/Jail.h
@@ -4,7 +4,8 @@
 
 ======================================== */
 
-#pragma once
+#ifndef SYSTEMKIT_JAIL_H
+#define SYSTEMKIT_JAIL_H
 
 #include <libSystem/SystemKit/System.h>
 
@@ -34,3 +35,5 @@ struct JAIL {
 /// @brief Get the current jail
 /// @return Pointer to the current jail structure, or NULL if not in a jail
 IMPORT_C struct JAIL* JailGetCurrent(Void);
+
+#endif
diff --git a/src/libSystem/SystemKit/Macros.h b/src/libSystem/SystemKit/Macros.h
index b30db701..dab30384 100644
--- a/src/libSystem/SystemKit/Macros.h
+++ b/src/libSystem/SystemKit/Macros.h
@@ -7,7 +7,8 @@ Purpose: libsci Macros header.
 
 ======================================== */
 
-#pragma once
+#ifndef SYSTEMKIT_MACROS_H
+#define SYSTEMKIT_MACROS_H
 
 /***********************************************************************************/
 /// @file libSystem/Macros.h
@@ -124,3 +125,5 @@ typedef nullPtr           NullPtr;
 #define LIBSYS_UNUSED(X) ((void) X)
 
 IMPORT_C void _rtl_assert(Bool expr, const Char* origin);
+
+#endif
diff --git a/src/libSystem/SystemKit/Syscall.h b/src/libSystem/SystemKit/Syscall.h
index 58d7d7f1..1d30782f 100644
--- a/src/libSystem/SystemKit/Syscall.h
+++ b/src/libSystem/SystemKit/Syscall.h
@@ -4,7 +4,8 @@
 
 ======================================== */
 
-#pragma once
+#ifndef SYSTEMKIT_SYSCALL_H
+#define SYSTEMKIT_SYSCALL_H
 
 #include <libSystem/SystemKit/System.h>
 #include <cstdarg>
@@ -19,3 +20,5 @@ IMPORT_C UInt64 libsys_hash_64(const Char* path);
 #ifndef SYSCALL_HASH
 #define SYSCALL_HASH(str) libsys_hash_64(str)
 #endif  // !SYSCALL_HASH
+
+#endif
diff --git a/src/libSystem/SystemKit/Verify.h b/src/libSystem/SystemKit/Verify.h
index c584ac82..0bdfd2ca 100644
--- a/src/libSystem/SystemKit/Verify.h
+++ b/src/libSystem/SystemKit/Verify.h
@@ -7,7 +7,8 @@
 
    ======================================== */
 
-#pragma once
+#ifndef SYSTEMKIT_VERIFY_H
+#define SYSTEMKIT_VERIFY_H
 
 #include <libSystem/SystemKit/System.h>
 
@@ -15,14 +16,11 @@ namespace LibSystem::Verify {
 /// @author 0xf00sec, and Amlal El Mahrouss
 /// @brief safe cast operator.
 template <class T, class R>
-inline R sys_safe_cast(const T* ptr) {
+inline R* sys_safe_cast(const T* ptr) {
   ::_rtl_assert(ptr, "safe cast failed!");
   return static_cast<R*>(const_cast<T*>(ptr));
 }
 
-template <class T, class R = Void>
-inline Void sys_safe_cast(const T* ptr) = delete;
-
 template <class T, class U>
 struct is_castable {
   using return_type = U;
@@ -45,3 +43,5 @@ constexpr R* sys_constexpr_cast(T* ptr) {
   return static_cast<R*>(ptr);
 }
 }  // namespace LibSystem::Verify
+
+#endif
diff --git a/src/libSystem/src/SystemCalls.cc b/src/libSystem/src/SystemCalls.cc
index 95545cde..c9dc1c52 100644
--- a/src/libSystem/src/SystemCalls.cc
+++ b/src/libSystem/src/SystemCalls.cc
@@ -123,7 +123,7 @@ IMPORT_C VoidPtr MmFillMemory(_Input VoidPtr dest, _Input UInt64 len, _Input UIn
 
 IMPORT_C Ref IoOpenFile(_Input const Char* path, _Input const Char* drv_letter) {
   return static_cast<Ref>(libsys_syscall_arg_3(
-      SYSCALL_HASH("IoOpenFile"), Verify::sys_safe_cast(path), Verify::sys_safe_cast(drv_letter)));
+      SYSCALL_HASH("IoOpenFile"), Verify::sys_safe_cast<Char, Void>(path), Verify::sys_safe_cast<Char, Void>(drv_letter)));
 }
 
 IMPORT_C Void IoCloseFile(_Input Ref desc) {
@@ -159,7 +159,7 @@ IMPORT_C SInt32 PrintOut(_Input IORef desc, const Char* fmt, ...) {
 
   // if truncated, `needed` >= kBufferSz; we still send truncated buffer
   auto ret_ptr = libsys_syscall_arg_3(SYSCALL_HASH("PrintOut"), static_cast<VoidPtr>(desc),
-                                      Verify::sys_safe_cast(buf));
+                                      Verify::sys_safe_cast<Char, Void>(buf));
 
   if (!ret_ptr) return -kErrorInvalidData;