diff --git a/ctypes_generation/definitions/winstruct.txt b/ctypes_generation/definitions/winstruct.txt
index a74b705..66bb92d 100644
--- a/ctypes_generation/definitions/winstruct.txt
+++ b/ctypes_generation/definitions/winstruct.txt
@@ -29,7 +29,8 @@ typedef struct _PEB {
   BYTE                          Reserved1[2];
   BYTE                          BeingDebugged;
   BYTE                          Reserved2[1];
-  PVOID                         Reserved3[2];
+  PVOID                         Mutant;
+  PVOID                         ImageBaseAddress;
   PPEB_LDR_DATA                 Ldr;
   PRTL_USER_PROCESS_PARAMETERS  ProcessParameters;
   BYTE                          Reserved4[104];
diff --git a/windows/generated_def/winstructs.py b/windows/generated_def/winstructs.py
index 901aba8..1302c8b 100644
--- a/windows/generated_def/winstructs.py
+++ b/windows/generated_def/winstructs.py
@@ -943,7 +943,8 @@ class _PEB(Structure):
         ("Reserved1", BYTE * 2),
         ("BeingDebugged", BYTE),
         ("Reserved2", BYTE * 1),
-        ("Reserved3", PVOID * 2),
+        ("Mutant", PVOID),
+        ("ImageBaseAddress", PVOID),
         ("Ldr", PPEB_LDR_DATA),
         ("ProcessParameters", PRTL_USER_PROCESS_PARAMETERS),
         ("Reserved4", BYTE * 104),