diff --git a/Docs/src/history.but b/Docs/src/history.but
index 3dbc638b..18e81833 100644
--- a/Docs/src/history.but
+++ b/Docs/src/history.but
@@ -6,6 +6,10 @@ Released on ?, 2014
 
 \S1{v3.0b1-cl} Changelog
 
+\S2{} Minor Changes
+
+\b Fixed POSIX !searchparse bug (\W{http://sf.net/p/nsis/patches/251}{patch #251})
+
 \S2{} Translations
 
 \b Added Armenian (Hrant Ohanyan)
diff --git a/Source/lang.cpp b/Source/lang.cpp
index 59d64749..c75d95bc 100644
--- a/Source/lang.cpp
+++ b/Source/lang.cpp
@@ -848,7 +848,7 @@ static void CreatePlatformStrfmt(const TCHAR *templ, TCHAR *out) {
     if (*out == L'%' && *templ == L's')
     {
       out++, templ++;
-      unsigned int cch = my_strncpy(out, NPRIs, -1);
+      size_t cch = my_strncpy(out, NPRIs, -1);
       out += --cch; // --cch because for loop does out++
     }
   }
diff --git a/Source/script.cpp b/Source/script.cpp
index 88e85152..c81a78ad 100644
--- a/Source/script.cpp
+++ b/Source/script.cpp
@@ -3470,13 +3470,8 @@ int CEXEBuild::doCommand(int which_token, LineParser &line)
           int i;
           for (i=0;i<list->getnum(); i ++)
           {
-            TCHAR *def=list->getname(i);
-            TCHAR *val=list->getvalue(i);
-            if (def && val)
-            {
-              if (definedlist.find(def)) definedlist.del(def);
-              definedlist.add(def,val);
-            }
+            TCHAR *def=list->getname(i), *val=list->getvalue(i);
+            if (def && val) definedlist.set(def,val);
           }
         }
         delete list;
@@ -6791,6 +6786,7 @@ int CEXEBuild::do_add_file_create_dir(const tstring& local_dir, const tstring& d
 
 DefineList *CEXEBuild::searchParseString(const TCHAR *source_string, LineParser&line, int parmOffs, bool ignCase, bool noErrors, UINT*failParam)
 {
+  const bool allowEmptyFirstTok = true;
   if (failParam) *failParam = 0;
   DefineList *ret = NULL;
   const TCHAR *defout = 0, *src_start = 0, *tok;
@@ -6799,7 +6795,7 @@ DefineList *CEXEBuild::searchParseString(const TCHAR *source_string, LineParser&
   {
     tok = line.gettoken_str(parmOffs++);
     const bool lasttoken = parmOffs > line.getnumtokens();
-    if (!tok || !*tok)
+    if (!*tok)
       tok = 0, maxlen = -1; // No more tokens to search for, save the rest of the string
     else
     {
@@ -6813,17 +6809,10 @@ DefineList *CEXEBuild::searchParseString(const TCHAR *source_string, LineParser&
       if (maxlen < 0)
         ret->add(defout,src_start);
       else
-      {
-        TCHAR *p = _tcsdup(src_start);
-        if (p)
-        {
-          p[maxlen] = 0;
-          ret->add(defout,p);
-          free(p);
-        }
-      }
+        ret->addn(defout,maxlen,src_start);
     }
-    if (!*source_string || (!tok && !lasttoken)) // We did not find the requested token!
+    if (!tok && lasttoken) break;
+    if (!*source_string || (allowEmptyFirstTok ? false : !tok)) // We did not find the requested token!
     {
       if (failParam) *failParam = ret ? ret->getnum() : 0;
       if (noErrors) break; // Caller is OK with a incomplete list of matched strings
@@ -6832,7 +6821,6 @@ DefineList *CEXEBuild::searchParseString(const TCHAR *source_string, LineParser&
       delete ret;
       return NULL;
     }
-    if (maxlen < 0) break;
     defout = line.gettoken_str(parmOffs++), src_start = source_string += toklen;
   }
   return ret;
diff --git a/Source/strlist.cpp b/Source/strlist.cpp
index 5e0349bc..f9861caa 100644
--- a/Source/strlist.cpp
+++ b/Source/strlist.cpp
@@ -18,9 +18,7 @@
 
 #include "strlist.h"
 #include "utf.h"
-#ifndef NDEBUG
 #include "util.h" // For PrintColorFmtMsg_ERR
-#endif
 
 #ifdef _UNICODE
 char* convert_processed_string_to_ansi(char *out, const TCHAR *in, WORD codepage); // defined in build.cpp
@@ -300,38 +298,37 @@ DefineList::~DefineList()
   struct define *s=(struct define*) m_gr.get();
   int num=m_gr.getlen()/sizeof(struct define);
 
-  for (int i=0; i<num; i++) {
-    free(s[i].value);
-  }
+  for (int i=0; i<num; i++) free(s[i].value);
 }
 
-int DefineList::add(const TCHAR *name, const TCHAR *value/*=_T("")*/)
+int DefineList::addn(const TCHAR *name, size_t maxvallen, const TCHAR *value)
 {
   int pos=SortedStringList<struct define>::add(name);
-  if (pos == -1)
-  {
-    return 1;
-  }
+  if (pos == -1) return 1;
 
+  size_t cbVal = ++maxvallen * sizeof(TCHAR);
   TCHAR **newvalue=&(((struct define*) m_gr.get())[pos].value);
-  size_t size_in_bytes = (_tcslen(value) + 1) * sizeof(TCHAR);
-
-  *newvalue=(TCHAR*)malloc(size_in_bytes);
 
+  *newvalue = (TCHAR*)malloc(cbVal);
   if (!(*newvalue))
   {
     extern int g_display_errors;
     extern void quit();
     if (g_display_errors)
     {
-      PrintColorFmtMsg_ERR(_T("\nInternal compiler error #12345: DefineList malloc(%lu) failed.\n"), (unsigned long) size_in_bytes);
+      PrintColorFmtMsg_ERR(_T("\nInternal compiler error #12345: DefineList malloc(%lu) failed.\n"), BUGBUG64TRUNCATE(unsigned long,cbVal));
     }
     quit();
   }
-  _tcscpy(*newvalue,value);
+  my_strncpy(*newvalue, value, maxvallen);
   return 0;
 }
 
+int DefineList::add(const TCHAR *name, const TCHAR *value/*=_T("")*/)
+{
+  return addn(name, _tcslen(value), value);
+}
+
 void DefineList::set(const TCHAR *name, const TCHAR *value/*=_T("")*/)
 {
   del(name);
diff --git a/Source/strlist.h b/Source/strlist.h
index 1d894d5e..c2900c06 100644
--- a/Source/strlist.h
+++ b/Source/strlist.h
@@ -476,6 +476,7 @@ class DefineList : public SortedStringList<struct define>
      * general program exit with error logging.
      */
     int add(const TCHAR *name, const TCHAR *value=_T(""));
+    int addn(const TCHAR *name, size_t maxvallen, const TCHAR *value); // maxvallen does not include \0
     void set(const TCHAR *name, const TCHAR *value=_T(""));
 
 	 /**
diff --git a/Source/util.cpp b/Source/util.cpp
index 75874bf7..270a883b 100644
--- a/Source/util.cpp
+++ b/Source/util.cpp
@@ -67,21 +67,13 @@ double my_wtof(const wchar_t *str)
   return atof(buf);
 }
 
-unsigned int my_strncpy(TCHAR*Dest, const TCHAR*Src, unsigned int cchMax)
+size_t my_strncpy(TCHAR*Dest, const TCHAR*Src, size_t cchMax)
 {
   // Dest and Src must be valid, Dest is always \0 terminated.
-  // Returns number of TCHARs copied to Dest; min(strlen(Src),cchMax-1).
-  unsigned int cch = 0;
-  if (cchMax)
-  {
-    for(;--cchMax;)
-    {
-      TCHAR ch = Src[cch];
-      if (!ch) break;
-      Dest[cch++] = ch;
-    }
-    Dest[cch] = _T('\0');
-  }
+  // Returns number of TCHARs copied to Dest (not counting \0); min(strlen(Src),cchMax-1).
+  size_t cch = 0;
+  if (cchMax) for (TCHAR c; --cchMax;) if (!(c = Src[cch])) break; else Dest[cch++] = c;
+  Dest[cch] = _T('\0');
   return cch;
 }
 
diff --git a/Source/util.h b/Source/util.h
index f249c4d2..d0cd9bce 100644
--- a/Source/util.h
+++ b/Source/util.h
@@ -33,7 +33,7 @@
 #include <stdarg.h>
 
 extern double my_wtof(const wchar_t *str);
-extern unsigned int my_strncpy(TCHAR*Dest, const TCHAR*Src, unsigned int cchMax);
+extern size_t my_strncpy(TCHAR*Dest, const TCHAR*Src, size_t cchMax);
 size_t my_strftime(TCHAR *s, size_t max, const TCHAR  *fmt, const struct tm *tm);
 
 // Adds the bitmap in filename using resource editor re as id id.