diff --git a/dll/win32/kernel32/client/proc.c b/dll/win32/kernel32/client/proc.c
index 9b680eb533..3a64794943 100644
--- a/dll/win32/kernel32/client/proc.c
+++ b/dll/win32/kernel32/client/proc.c
@@ -1659,7 +1659,8 @@ WINAPI
 GetPriorityClass(IN HANDLE hProcess)
 {
     NTSTATUS Status;
-    PROCESS_PRIORITY_CLASS PriorityClass;
+    PROCESS_PRIORITY_CLASS DECLSPEC_ALIGN(4) PriorityClass;
+    C_ASSERT(sizeof(PriorityClass) == 2);
 
     /* Query the kernel */
     Status = NtQueryInformationProcess(hProcess,
@@ -1696,7 +1697,8 @@ SetPriorityClass(IN HANDLE hProcess,
 {
     NTSTATUS Status;
     PVOID State = NULL;
-    PROCESS_PRIORITY_CLASS PriorityClass;
+    PROCESS_PRIORITY_CLASS DECLSPEC_ALIGN(4) PriorityClass;
+    C_ASSERT(sizeof(PriorityClass) == 2);
 
     /* Handle conversion from Win32 to NT priority classes */
     switch (dwPriorityClass)
@@ -2270,7 +2272,7 @@ CreateProcessInternalW(IN HANDLE hUserToken,
     HANDLE DebugHandle, TokenHandle, JobHandle, KeyHandle, ThreadHandle;
     HANDLE FileHandle, SectionHandle, ProcessHandle;
     ULONG ResumeCount;
-    PROCESS_PRIORITY_CLASS PriorityClass;
+    PROCESS_PRIORITY_CLASS DECLSPEC_ALIGN(4) PriorityClass;
     NTSTATUS Status, AppCompatStatus, SaferStatus, IFEOStatus, ImageDbgStatus;
     PPEB Peb, RemotePeb;
     PTEB Teb;
@@ -2342,6 +2344,8 @@ CreateProcessInternalW(IN HANDLE hUserToken,
     BOOLEAN IsWowApp;
     PBASE_CHECK_VDM CheckVdmMsg;
 
+    C_ASSERT(sizeof(PriorityClass) == 2);
+
     /* Zero out the initial core variables and handles */
     QuerySection = FALSE;
     InJob = FALSE;
diff --git a/sdk/include/ndk/pstypes.h b/sdk/include/ndk/pstypes.h
index 55839aca37..d10199097a 100644
--- a/sdk/include/ndk/pstypes.h
+++ b/sdk/include/ndk/pstypes.h
@@ -910,12 +910,15 @@ typedef struct _PROCESS_SESSION_INFORMATION
 
 #endif
 
-typedef struct DECLSPEC_ALIGN(4) _PROCESS_PRIORITY_CLASS
+typedef struct _PROCESS_PRIORITY_CLASS
 {
     BOOLEAN Foreground;
     UCHAR PriorityClass;
 } PROCESS_PRIORITY_CLASS, *PPROCESS_PRIORITY_CLASS;
 
+// Compatibility with windows, see CORE-16757, CORE-17106, CORE-17247
+C_ASSERT(sizeof(PROCESS_PRIORITY_CLASS) == 2);
+
 typedef struct _PROCESS_FOREGROUND_BACKGROUND
 {
     BOOLEAN Foreground;