diff --git a/src/p_exe.cpp b/src/p_exe.cpp
index 0fbd436d..316e5625 100644
--- a/src/p_exe.cpp
+++ b/src/p_exe.cpp
@@ -85,14 +85,14 @@ int PackExe::fillExeHeader(struct exe_header_t *eh) const
     oh.headsize16 = 2;
     oh.ip = 0;
 
-    unsigned destpara = (ph.u_len + ph.overlap_overhead - ph.c_len + 31) / 16;
+    oh.sp = ih.sp > 0x200 ? ih.sp : 0x200;
 
+    unsigned destpara = (ph.u_len + ph.overlap_overhead - ph.c_len + 31) / 16;
     oh.ss = ph.c_len/16 + destpara;
     if (ih.ss*16 + ih.sp < 0x100000 && ih.ss > oh.ss && ih.sp > 0x200)
         oh.ss = ih.ss;
-    oh.sp = ih.sp > 0x200 ? ih.sp : 0x200;
-    if (oh.ss*16u + 0x50 < ih.ss*16u + ih.sp
-        && oh.ss*16u + 0x200 > ih.ss*16u + ih.sp)
+    if (oh.ss*16 + 0x50 < ih.ss*16 + ih.sp
+        && oh.ss*16 + 0x200 > ih.ss*16 + ih.sp)
         oh.ss += 0x20;
 
     if (oh.ss != ih.ss)
@@ -398,8 +398,6 @@ void PackExe::pack(OutputFile *fo)
     if (ph.max_run_found + ph.max_match_found > 0x8000)
         throwCantPack("decompressor limit exceeded, send a bugreport");
 
-    ph.overlap_overhead = findOverlapOverhead(obuf,32);
-
 #ifdef TESTING
     if (opt->debug)
     {
@@ -411,8 +409,10 @@ void PackExe::pack(OutputFile *fo)
     }
 #endif
 
-    int flag = fillExeHeader(&oh);
+    ph.overlap_overhead = findOverlapOverhead(obuf,32);
     const unsigned lsize = buildLoader(&ft);
+    int flag = fillExeHeader(&oh);
+
     MemBuffer loader(lsize);
     memcpy(loader,getLoader(),lsize);
     //OutputFile::dump("xxloader.dat", loader, lsize);
@@ -428,8 +428,8 @@ void PackExe::pack(OutputFile *fo)
 
     // set oh.min & oh.max
     ic = ih.min*16 + ih_imagesize;
-    if (ic < oh.ss*16u + oh.sp)
-        ic = oh.ss*16u + oh.sp;
+    if (ic < oh.ss*16 + oh.sp)
+        ic = oh.ss*16 + oh.sp;
     oh.min = (ic - (packedsize + lsize)) / 16;
     ic = oh.min + (ih.max - ih.min);
     oh.max = ic < 0xffff && ih.max != 0xffff ? ic : 0xffff;
diff --git a/src/packhead.cpp b/src/packhead.cpp
index d4bddd5c..419255aa 100644
--- a/src/packhead.cpp
+++ b/src/packhead.cpp
@@ -38,7 +38,7 @@
 **************************************************************************/
 
 PackHeader::PackHeader() :
-    version(-1), format(-1), filter(0), filter_cto(0), overlap_overhead(0)
+    version(-1), format(-1)
 {
 }
 
@@ -108,6 +108,7 @@ void PackHeader::putPackHeader(upx_bytep p)
     throwBadLoader();
 #else
     assert(get_le32(p) == UPX_MAGIC_LE32);
+    int size = 0;
 
     p[4] = (unsigned char) version;
     p[5] = (unsigned char) format;
@@ -124,13 +125,19 @@ void PackHeader::putPackHeader(upx_bytep p)
             set_le16(p+16,u_len);
             set_le16(p+18,c_len);
             p[20] = (unsigned char) filter;
+            size = 22;
         }
-        else if (format == UPX_F_DOS_EXE || format == UPX_F_DOS_EXEH)
+        else if (format == UPX_F_DOS_EXE)
         {
             set_le24(p+16,u_len);
             set_le24(p+19,c_len);
             set_le24(p+22,u_file_size);
             p[25] = (unsigned char) filter;
+            size = 27;
+        }
+        else if (format == UPX_F_DOS_EXEH)
+        {
+            throwInternalError("invalid format");
         }
         else
         {
@@ -140,6 +147,7 @@ void PackHeader::putPackHeader(upx_bytep p)
             p[28] = (unsigned char) filter;
             p[29] = (unsigned char) filter_cto;
             p[30] = 0;
+            size = 32;
         }
     }
     else
@@ -152,10 +160,11 @@ void PackHeader::putPackHeader(upx_bytep p)
         p[28] = (unsigned char) filter;
         p[29] = (unsigned char) filter_cto;
         p[30] = 0;
+        size = 32;
     }
 
     // store header_checksum
-    const int size = getPackHeaderSize();
+    assert(size == getPackHeaderSize());
     p[size - 1] = get_packheader_checksum(p, size - 1);
 #endif /* UNUPX */
 }