diff --git a/src/filter.cpp b/src/filter.cpp
index 5a5d02c6..0631242b 100644
--- a/src/filter.cpp
+++ b/src/filter.cpp
@@ -95,7 +95,6 @@ void Filter::init(int id_, unsigned addvalue_)
     initFilter(this, NULL, 0);
     // clear input parameters
     this->addvalue = addvalue_;
-    this->forced_cto = -1;
     this->preferred_ctos = NULL;
     // clear input/output parameters
     this->cto = 0;
diff --git a/src/filter.h b/src/filter.h
index abd77218..e47d1739 100644
--- a/src/filter.h
+++ b/src/filter.h
@@ -75,7 +75,6 @@ public:
 
     // Input parameters used by various filters.
     unsigned addvalue;
-    int forced_cto;
     const int *preferred_ctos;
 
     // Input/output parameters used by various filters
diff --git a/src/filter/ctjo.h b/src/filter/ctjo.h
index 919d8f98..41081eca 100644
--- a/src/filter/ctjo.h
+++ b/src/filter/ctjo.h
@@ -45,64 +45,27 @@ static int F(Filter *f)
     const unsigned size = f->buf_len;
 
     unsigned ic, jc, kc;
-    unsigned cto;
-    unsigned char cto8;
     unsigned calls = 0, noncalls = 0, noncalls2 = 0;
     unsigned lastnoncall = size, lastcall = 0;
 
     // find a 16MB large empty address space
-    if (f->forced_cto >= 0 && f->forced_cto <= 255)
-        cto8 = (unsigned char) f->forced_cto;
-    else
     {
         unsigned char buf[256];
         memset(buf,0,256);
 
-#if 1
         for (ic = 0; ic < size - 5; ic++)
             if (COND(b,ic,lastcall) && get_le32(b+ic+1)+ic+1 >= size)
             {
                 buf[b[ic+1]] |= 1;
             }
-#else
-        {
-            int i = size - 6;
-            do {
-                if (COND(b,i,lastcall) && get_le32(b+i+1)+i+1 >= size)
-                    buf[b[i+1]] |= 1;
-            } while (--i >= 0);
-        }
-#endif
 
-        ic = 256;
-        if (f->preferred_ctos)
-        {
-            for (const int *pc = f->preferred_ctos; *pc >= 0; pc++)
-            {
-                if (buf[*pc & 255] == 0)
-                {
-                    ic = *pc & 255;
-                    break;
-                }
-            }
-        }
-#if 0
-        // just a test to see if certain ctos would improve compression
-        if (ic >= 256)
-            for (ic = 0; ic < 256; ic += 16)
-                if (buf[ic] == 0)
-                    break;
-#endif
-        if (ic >= 256)
-            for (ic = 0; ic < 256; ic++)
-                if (buf[ic] == 0)
-                    break;
-        if (ic >= 256)
-            //throwCantPack("call trick problem");
+        if (getcto(f, buf) < 0)
             return -1;
-        cto8 = (unsigned char) ic;
     }
-    cto = (unsigned)cto8 << 24;
+    const unsigned char cto8 = f->cto;
+#ifdef U
+    const unsigned cto = (unsigned)cto8 << 24;
+#endif
 
     for (ic = 0; ic < size - 5; ic++)
     {
@@ -146,7 +109,6 @@ static int F(Filter *f)
         }
     }
 
-    f->cto = cto8;
     f->calls = calls;
     f->noncalls = noncalls;
     f->lastcall = lastcall;
@@ -168,7 +130,7 @@ static int U(Filter *f)
     upx_byte *b = f->buf;
     const unsigned size5 = f->buf_len - 5;
     const unsigned addvalue = f->addvalue;
-    const unsigned cto = f->cto << 24;
+    const unsigned cto = (unsigned)f->cto << 24;
     unsigned lastcall = 0;
 
     unsigned ic, jc;
diff --git a/src/filter/ctjor.h b/src/filter/ctjor.h
index 182a9d59..1213bb23 100644
--- a/src/filter/ctjor.h
+++ b/src/filter/ctjor.h
@@ -29,8 +29,9 @@
 
 
 /*************************************************************************
-//
+// filter / scan
 **************************************************************************/
+
 #ifdef U  //{
 static int const N_MRU = 1024;  // does not have to be a power of 2
 
@@ -61,6 +62,7 @@ update_mru(
 }
 #endif  //}
 
+
 static int F(Filter *f)
 {
 #ifdef U
@@ -74,8 +76,6 @@ static int F(Filter *f)
     const unsigned size = f->buf_len;
 
     unsigned ic, jc, kc;
-    unsigned cto;
-    unsigned char cto8;
     unsigned calls = 0, noncalls = 0, noncalls2 = 0;
     unsigned lastnoncall = size, lastcall = 0;
 
@@ -87,58 +87,23 @@ static int F(Filter *f)
 
     // FIXME: We must fit into 8MB because we steal one bit.
     // find a 16MB large empty address space
-    if (f->forced_cto >= 0 && f->forced_cto <= 255)
-        cto8 = (unsigned char) f->forced_cto;
-    else
     {
         unsigned char buf[256];
         memset(buf,0,256);
 
-#if 1
         for (ic = 0; ic < size - 5; ic++)
             if (CONDF(b,ic,lastcall) && get_le32(b+ic+1)+ic+1 >= size)
             {
                 buf[b[ic+1]] |= 1;
             }
-#else
-        {
-            int i = size - 6;
-            do {
-                if (CONDF(b,i,lastcall) && get_le32(b+i+1)+i+1 >= size)
-                    buf[b[i+1]] |= 1;
-            } while (--i >= 0);
-        }
-#endif
 
-        ic = 256;
-        if (f->preferred_ctos)
-        {
-            for (const int *pc = f->preferred_ctos; *pc >= 0; pc++)
-            {
-                if (buf[*pc & 255] == 0)
-                {
-                    ic = *pc & 255;
-                    break;
-                }
-            }
-        }
-#if 0
-        // just a test to see if certain ctos would improve compression
-        if (ic >= 256)
-            for (ic = 0; ic < 256; ic += 16)
-                if (buf[ic] == 0)
-                    break;
-#endif
-        if (ic >= 256)
-            for (ic = 0; ic < 256; ic++)
-                if (buf[ic] == 0)
-                    break;
-        if (ic >= 256)
-            //throwCantPack("call trick problem");
+        if (getcto(f, buf) < 0)
             return -1;
-        cto8 = (unsigned char) ic;
     }
-    cto = (unsigned)cto8 << 24;
+    const unsigned char cto8 = f->cto;
+#ifdef U
+    const unsigned cto = (unsigned)cto8 << 24;
+#endif
 
     for (ic = 0; ic < size - 5; ic++)
     {
@@ -226,7 +191,6 @@ static int F(Filter *f)
         }
     }
 
-    f->cto = cto8;
     f->calls = calls;
     f->noncalls = noncalls;
     f->lastcall = lastcall;
@@ -238,6 +202,10 @@ static int F(Filter *f)
 }
 
 
+/*************************************************************************
+// unfilter
+**************************************************************************/
+
 #ifdef U
 static int U(Filter *f)
 {
@@ -246,7 +214,7 @@ static int U(Filter *f)
     upx_byte *const b = f->buf;
     const unsigned size5 = f->buf_len - 5;
     const unsigned addvalue = f->addvalue;
-    const unsigned cto = f->cto << 24;
+    const unsigned cto = (unsigned)f->cto << 24;
     unsigned lastcall = 0;
     int hand = 0, tail = 0;
     unsigned mru[N_MRU];
diff --git a/src/filter/cto.h b/src/filter/cto.h
index cd9b716c..8ff610f4 100644
--- a/src/filter/cto.h
+++ b/src/filter/cto.h
@@ -44,64 +44,27 @@ static int F(Filter *f)
     const unsigned size = f->buf_len;
 
     unsigned ic, jc, kc;
-    unsigned cto;
-    unsigned char cto8;
     unsigned calls = 0, noncalls = 0, noncalls2 = 0;
     unsigned lastnoncall = size, lastcall = 0;
 
     // find a 16MB large empty address space
-    if (f->forced_cto >= 0 && f->forced_cto <= 255)
-        cto8 = (unsigned char) f->forced_cto;
-    else
     {
         unsigned char buf[256];
         memset(buf,0,256);
 
-#if 1
         for (ic = 0; ic < size - 5; ic++)
             if (COND(b,ic) && get_le32(b+ic+1)+ic+1 >= size)
             {
                 buf[b[ic+1]] |= 1;
             }
-#else
-        {
-            int i = size - 6;
-            do {
-                if (COND(b,i) && get_le32(b+i+1)+i+1 >= size)
-                    buf[b[i+1]] |= 1;
-            } while (--i >= 0);
-        }
-#endif
 
-        ic = 256;
-        if (f->preferred_ctos)
-        {
-            for (const int *pc = f->preferred_ctos; *pc >= 0; pc++)
-            {
-                if (buf[*pc & 255] == 0)
-                {
-                    ic = *pc & 255;
-                    break;
-                }
-            }
-        }
-#if 0
-        // just a test to see if certain ctos would improve compression
-        if (ic >= 256)
-            for (ic = 0; ic < 256; ic += 16)
-                if (buf[ic] == 0)
-                    break;
-#endif
-        if (ic >= 256)
-            for (ic = 0; ic < 256; ic++)
-                if (buf[ic] == 0)
-                    break;
-        if (ic >= 256)
-            //throwCantPack("call trick problem");
+        if (getcto(f, buf) < 0)
             return -1;
-        cto8 = (unsigned char) ic;
     }
-    cto = (unsigned)cto8 << 24;
+    const unsigned char cto8 = f->cto;
+#ifdef U
+    const unsigned cto = (unsigned)f->cto << 24;
+#endif
 
     for (ic = 0; ic < size - 5; ic++)
     {
@@ -145,7 +108,6 @@ static int F(Filter *f)
         }
     }
 
-    f->cto = cto8;
     f->calls = calls;
     f->noncalls = noncalls;
     f->lastcall = lastcall;
@@ -167,7 +129,7 @@ static int U(Filter *f)
     upx_byte *b = f->buf;
     const unsigned size5 = f->buf_len - 5;
     const unsigned addvalue = f->addvalue;
-    const unsigned cto = f->cto << 24;
+    const unsigned cto = (unsigned)f->cto << 24;
 
     unsigned ic, jc;
 
diff --git a/src/filter/getcto.h b/src/filter/getcto.h
new file mode 100644
index 00000000..4a96e9f8
--- /dev/null
+++ b/src/filter/getcto.h
@@ -0,0 +1,75 @@
+/* getcto.h -- calltrick util
+
+   This file is part of the UPX executable compressor.
+
+   Copyright (C) 1996-2001 Markus Franz Xaver Johannes Oberhumer
+   Copyright (C) 1996-2001 Laszlo Molnar
+   All Rights Reserved.
+
+   UPX and the UCL library are free software; you can redistribute them
+   and/or modify them under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2 of
+   the License, or (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.
+   If not, write to the Free Software Foundation, Inc.,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+
+   Markus F.X.J. Oberhumer   Laszlo Molnar
+   markus@oberhumer.com      ml1050@cdata.tvnet.hu
+ */
+
+
+
+/*************************************************************************
+//
+**************************************************************************/
+
+static int getcto(Filter *f, const unsigned char *buf, const int n=256)
+{
+    int ic = n;
+
+    if (f->preferred_ctos)
+    {
+        for (const int *pc = f->preferred_ctos; *pc >= 0; pc++)
+        {
+            if (*pc < n && buf[*pc] == 0)
+            {
+                ic = *pc;
+                break;
+            }
+        }
+    }
+
+#if 0
+    // just a test to see if certain ctos would improve compression
+    if (ic >= n)
+        for (ic = 0; ic < n; ic += 16)
+            if (buf[ic] == 0)
+                break;
+#endif
+    if (ic >= n)
+        for (ic = 0; ic < n; ic++)
+            if (buf[ic] == 0)
+                break;
+
+    if (ic >= n)
+        //throwCantPack("call trick problem");
+        return -1;
+
+    f->cto = (unsigned char) ic;
+    return ic;
+}
+
+
+
+/*
+vi:ts=4:et:nowrap
+*/
+
diff --git a/src/filteri.cpp b/src/filteri.cpp
index 4e685ad6..74e94fbd 100644
--- a/src/filteri.cpp
+++ b/src/filteri.cpp
@@ -32,6 +32,9 @@
 
 #define set_dummy(p, v)     ((void)0)
 
+// util
+#include "filter/getcto.h"
+
 
 /*************************************************************************
 // calltrick / swaptrick