diff --git a/Source/exehead/Ui.c b/Source/exehead/Ui.c
index adc378e7..296f5bb2 100644
--- a/Source/exehead/Ui.c
+++ b/Source/exehead/Ui.c
@@ -751,8 +751,9 @@ static int NSISCALL getreqsize()
 
 static BOOL CALLBACK DirProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
-  char *dir = g_usrvars[g_this_page->parms[4]];
-  int browse_text = g_this_page->parms[3];
+  page *thispage = g_this_page;
+  char *dir = g_usrvars[thispage->parms[4]];
+  int browse_text = thispage->parms[3];
   if (uMsg == WM_NOTIFY_INIGO_MONTOYA)
   {
     GetUIText(IDC_DIR,dir,NSIS_MAX_STRLEN);
@@ -831,12 +832,13 @@ static BOOL CALLBACK DirProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPar
   {
     static char s[NSIS_MAX_STRLEN];
     char *p;
-    int is_valid_path;
+    int error = 0;
     int total, available=-1;
     DWORD spc,bps,fc,tc;
 
     GetUIText(IDC_DIR,dir,NSIS_MAX_STRLEN);
-    is_valid_path=is_valid_instpath(dir);
+    if (!is_valid_instpath(dir))
+      error = NSIS_INSTDIR_INVALID;
 
     mystrcpy(s,dir);
     p=skip_root(s);
@@ -852,6 +854,9 @@ static BOOL CALLBACK DirProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPar
 
     total = getreqsize();
 
+    if ((unsigned int)available < (unsigned int)total)
+      error = NSIS_INSTDIR_NOT_ENOUGH_SPACE;
+
     if (LANG_STR_TAB(LANG_SPACE_REQ)) {
       SetUITextNT(IDC_SPACEREQUIRED,inttosizestr(total,GetNSISString(s,LANG_SPACE_REQ)));
       if (available != -1)
@@ -860,12 +865,17 @@ static BOOL CALLBACK DirProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lPar
         SetUITextNT(IDC_SPACEAVAILABLE,"");
     }
 
-    EnableWindow(m_hwndOK,
-      is_valid_path && ((unsigned int)available >= (unsigned int)total)
+    g_exec_flags.instdir_error = error;
+
 #ifdef NSIS_SUPPORT_CODECALLBACKS
-      && !ExecuteCodeSegment(g_header->code_onVerifyInstDir,NULL)
+    if (!error)
+      error = ExecuteCodeSegment(g_header->code_onVerifyInstDir,NULL);
 #endif
-    );
+
+    if (thispage->flags & PF_DIR_NO_BTN_DISABLE)
+      error = 0;
+
+    EnableWindow(m_hwndOK, !error);
   }
   return HandleStaticBkColor();
 }
diff --git a/Source/exehead/exec.c b/Source/exehead/exec.c
index c725f430..caee4827 100644
--- a/Source/exehead/exec.c
+++ b/Source/exehead/exec.c
@@ -122,31 +122,43 @@ static int NSISCALL ExecuteEntry(entry *entry_)
   char *buf3 = bufs[3];
   char *buf4 = bufs[4];
 
-  int parm0 = entry_->offsets[0];
-  char *var0 = g_usrvars[parm0];
-  int parm1 = entry_->offsets[1];
-  char *var1 = g_usrvars[parm1];
-  int parm2 = entry_->offsets[2];
-  char *var2 = g_usrvars[parm2];
-  int parm3 = entry_->offsets[3];
-  char *var3 = g_usrvars[parm3];
-  int parm4 = entry_->offsets[4];
-//char *var4 = g_usrvars[parm4]; // not used yet
-  int parm5 = entry_->offsets[5];
-//char *var5 = g_usrvars[parm5]; // not used yet
-  int which = entry_->which;
-
-  // Saves 8 bytes
-  // HWND mainHwnd = g_hwnd;
-  // #define g_hwnd mainHwnd
+  char *var0;
+  char *var1;
+  char *var2;
+  char *var3;
+  //char *var4;
+  //char *var5;
 
 #ifdef NSIS_CONFIG_COMPONENTPAGE
   HWND hwSectionHack = g_SectionHack;
 #endif
 
+  // Saves 8 bytes
+  HWND mainHwnd = g_hwnd;
+#define g_hwnd mainHwnd
+
   int exec_error = 0;
 
-  parms = entry_->offsets;
+  entry lent;
+  mini_memcpy(&lent, entry_, sizeof(entry));
+
+#define which (lent.which)
+#define parm0 (lent.offsets[0])
+#define parm1 (lent.offsets[1])
+#define parm2 (lent.offsets[2])
+#define parm3 (lent.offsets[3])
+#define parm4 (lent.offsets[4])
+#define parm5 (lent.offsets[5])
+
+  var0 = g_usrvars[parm0];
+  var1 = g_usrvars[parm1];
+  var2 = g_usrvars[parm2];
+  var3 = g_usrvars[parm3];
+  // not used yet
+  //var4 = g_usrvars[parm4];
+  //var5 = g_usrvars[parm5];
+
+  parms = lent.offsets;
 
   switch (which)
   {
@@ -202,7 +214,7 @@ static int NSISCALL ExecuteEntry(entry *entry_)
     break;
     case EW_IFFLAG:
     {
-      int f=entry_->offsets[!g_exec_flags.flags[parm2]];
+      int f=lent.offsets[!g_exec_flags.flags[parm2]];
       g_exec_flags.flags[parm2]&=parm3;
       return f;
     }
@@ -377,7 +389,7 @@ static int NSISCALL ExecuteEntry(entry *entry_)
           int cmp=0;
           if (ffd)
           {
-            cmp=CompareFileTime(&ffd->ftLastWriteTime, (FILETIME*)(entry_->offsets + 3));
+            cmp=CompareFileTime(&ffd->ftLastWriteTime, (FILETIME*)(lent.offsets + 3));
           }
           overwriteflag=!(cmp & (0x80000000 | (overwriteflag - 3)));
         }
@@ -431,7 +443,7 @@ static int NSISCALL ExecuteEntry(entry *entry_)
         log_printf3("File: wrote %d to \"%s\"",ret,buf0);
 
         if (parm3 != 0xffffffff || parm4 != 0xffffffff)
-          SetFileTime(hOut,(FILETIME*)(entry_->offsets+3),NULL,(FILETIME*)(entry_->offsets+3));
+          SetFileTime(hOut,(FILETIME*)(lent.offsets+3),NULL,(FILETIME*)(lent.offsets+3));
 
         CloseHandle(hOut);
 
diff --git a/Source/exehead/fileform.h b/Source/exehead/fileform.h
index d40fcaab..efb36fb9 100644
--- a/Source/exehead/fileform.h
+++ b/Source/exehead/fileform.h
@@ -360,6 +360,7 @@ enum
 #define PF_LICENSE_SELECTED 1 // must be 1
 #define PF_NO_NEXT_FOCUS 128
 #define PF_PAGE_EX 512
+#define PF_DIR_NO_BTN_DISABLE 1024
 
 typedef struct
 {
@@ -448,6 +449,9 @@ DWORD NSISCALL SetSelfFilePointer(LONG lDistanceToMove);
   #endif
 #endif
 
+#define NSIS_INSTDIR_INVALID 1
+#define NSIS_INSTDIR_NOT_ENOUGH_SPACE 2
+
 union exec_flags {
   struct {
     int autoclose;
@@ -462,6 +466,7 @@ union exec_flags {
 #ifdef NSIS_CONFIG_SILENT_SUPPORT
     int silent;
 #endif
+    int instdir_error;
   };
   int flags[1];
 };
diff --git a/Source/script.cpp b/Source/script.cpp
index 41320205..6fa6c09a 100644
--- a/Source/script.cpp
+++ b/Source/script.cpp
@@ -1350,6 +1350,26 @@ int CEXEBuild::doCommand(int which_token, LineParser &line)
       SCRIPT_MSG("DirVar: %s\n", line.gettoken_str(1));
     }
     return make_sure_not_in_secorfunc(line.gettoken_str(0), 1);
+    case TOK_DIRVERIFY:
+    {
+      if (!cur_page || cur_page_type != PAGE_DIRECTORY) {
+        ERROR_MSG("Error: can't use DirVerify outside of PageEx directory.\n");
+        return PS_ERROR;
+      }
+      cur_page->flags &= ~PF_DIR_NO_BTN_DISABLE;
+      int k = line.gettoken_enum(1,"auto\0leave\0");
+      if (k == -1)
+        PRINTHELP();
+      if (k)
+        cur_page->flags |= PF_DIR_NO_BTN_DISABLE;
+      SCRIPT_MSG("DirVerify: %s\n", line.gettoken_str(1));
+    }
+    return make_sure_not_in_secorfunc(line.gettoken_str(0), 1);
+    case TOK_GETINSTDIRERROR:
+      ent.which = EW_GETFLAG;
+      ent.offsets[0] = GetUserVarIndex(line, 1);
+      ent.offsets[1] = FLAG_OFFSET(instdir_error);
+    return add_entry(&ent);
 #ifdef NSIS_CONFIG_COMPONENTPAGE
     case TOK_COMPTEXT:
       {
diff --git a/Source/tokens.cpp b/Source/tokens.cpp
index 746cea78..6bf731f3 100644
--- a/Source/tokens.cpp
+++ b/Source/tokens.cpp
@@ -49,6 +49,8 @@ static tokenType tokenlist[TOK__LAST] =
 {TOK_DIRTEXT,"DirText",0,4,"[directory_page_description] [directory_page_subtext] [browse_button_text] [browse_dlg_text]"},
 {TOK_DIRSHOW,"DirShow",1,0,"(show|hide)"},
 {TOK_DIRVAR,"DirVar",1,0,"$(user_var: dir in/out))"},
+{TOK_DIRVERIFY,"DirVerify",1,0,"auto|leave"},
+{TOK_GETINSTDIRERROR,"GetInstDirError",1,0,"$(user_var: error output)"},
 {TOK_ROOTDIRINST,"AllowRootDirInstall",1,0,"(true|false)"},
 {TOK_CHECKBITMAP,"CheckBitmap",1,0,"local_bitmap.bmp"},
 {TOK_ENABLEWINDOW,"EnableWindow",2,0,"hwnd (1|0)"},
diff --git a/Source/tokens.h b/Source/tokens.h
index abc37010..27a6bb67 100644
--- a/Source/tokens.h
+++ b/Source/tokens.h
@@ -109,8 +109,11 @@ enum
   TOK_PAGEEX,
   TOK_PAGEEXEND,
   TOK_DIRVAR,
+  TOK_DIRVERIFY,
   TOK_PAGECALLBACKS,
 
+  TOK_GETINSTDIRERROR,
+
   // flag setters
   TOK_SETDATESAVE,
   TOK_SETOVERWRITE,