diff --git a/Source/build.cpp b/Source/build.cpp
index a5ef47d4..43547e16 100644
--- a/Source/build.cpp
+++ b/Source/build.cpp
@@ -154,8 +154,8 @@ CEXEBuild::CEXEBuild() :
 #endif
   if (sizeof(void*) > 4) definedlist.add(_T("NSIS_MAKENSIS64"));
 
-  db_opt_save=db_opt_save_u=0;
-  db_comp_save=db_full_size=db_comp_save_u=db_full_size_u=0;
+  db_opt_save=db_opt_save_u=db_full_size=db_full_size_u=0;
+  db_comp_save=db_comp_save_u=0;
 
   // Added by Amir Szekely 31st July 2002
 #ifdef NSIS_CONFIG_COMPRESSION_SUPPORT
@@ -957,11 +957,7 @@ int CEXEBuild::add_db_data(IMMap *mmap) // returns offset
     {
       int oldst;
       if (datablock_finddata(*mmap, 0, length, &oldst))
-      {
-        // BUGBUG: Should we increase db_full_size? db_full_size = BUGBUG64TRUNCATE(int,db_full_size+length);
-        db_opt_save += length;
-        return oldst;
-      }
+        return (db_full_size += length, db_opt_save += length, oldst);
     }
 
     db->resize(st + sizeof(int) + length);
@@ -2819,12 +2815,12 @@ int CEXEBuild::write_output(void)
 
   if (db_opt_save)
   {
-    UINT32 disp_db_opt_save, total_out_size_estimate=
+    UINT32 total_out_size_estimate=
       m_exehead_size+sizeof(fh)+build_datablock.getlen()+(build_crcchk?sizeof(crc32_t):0);
     int pc=(int)((db_opt_save*1000)/(db_opt_save+total_out_size_estimate));
-    const TCHAR *disp_savedunit=GetFriendlySize(db_opt_save, disp_db_opt_save, true);
-    INFO_MSG(_T("Datablock optimizer saved %u %") NPRIs _T(" (~%d.%d%%).\n"),
-      disp_db_opt_save,disp_savedunit,pc/10,pc%10);
+    FriendlySize fs(db_opt_save);
+    INFO_MSG(_T("Datablock optimizer saved %u%") NPRIs _T(" (~%d.%d%%).\n"),
+      fs.UInt(),fs.Scale(),pc/10,pc%10);
   }
 
 #ifdef NSIS_CONFIG_COMPRESSION_SUPPORT
@@ -2848,19 +2844,25 @@ int CEXEBuild::write_output(void)
   total_usize+=sizeof(fh)+fh.length_of_header;
 
   {
-    unsigned int dbsize, dbsizeu;
+    unsigned int dbsize;
+    UINT64 dbsizeu;
     dbsize = build_datablock.getlen();
     if (uninstall_size>0) dbsize -= uninstall_size;
 
     if (build_compress_whole) {
       dbsizeu = dbsize;
-      INFO_MSG(_T("Install data:                          (%u bytes)\n"),dbsizeu);
+      INFO_MSG(_T("Install data:                          (%u bytes)\n"),dbsize); // dbsize==dbsizeu and is easy to print
     }
     else {
       dbsizeu = db_full_size - uninstall_size_full;
-      INFO_MSG(_T("Install data:             %10u / %u bytes\n"),dbsize,dbsizeu);
+      FriendlySize us(dbsizeu, GFSF_BYTESIFPOSSIBLE); // uncompressed installer size
+      FriendlySize cs(dbsize, GFSF_BYTESIFPOSSIBLE | (us.UInt()==dbsizeu ? GFSF_HIDEBYTESCALE : 0)); // compressed installer size
+      INFO_MSG(_T("Install data:             %10u%") NPRIs _T(" / %u%") NPRIs _T("\n"),
+        cs.UInt(),cs.Scale(),us.UInt(),us.Scale()); // "123 / 456 bytes" or "123 KiB / 456 MiB"
     }
-    total_usize += dbsizeu;
+    UINT future = (build_crcchk ? sizeof(int) : 0) + (uninstall_size > 0 ? uninstall_size_full : 0);
+    UINT maxsize = (~(UINT)0) - (total_usize + future), totsizadd = dbsizeu < maxsize ? (UINT)dbsizeu : maxsize;
+    total_usize += totsizadd; // Might not be accurate, it is more important to not overflow the additions coming up
   }
 
   if (uninstall_size>=0)
@@ -2980,9 +2982,10 @@ int CEXEBuild::write_output(void)
   }
   INFO_MSG(_T("\n"));
   {
-    UINT pc=(UINT)(((UINT64)ftell(fp)*1000)/(total_usize));
+    long fileend = ftell(fp);
+    UINT pc=(UINT)(((UINT64)fileend*1000)/(total_usize));
     INFO_MSG(_T("Total size:               %10u / %u bytes (%u.%u%%)\n"),
-      ftell(fp),total_usize,pc/10,pc%10);
+      fileend,total_usize,pc/10,pc%10);
   }
   fclose(fp);
   if (postbuild_cmds)
@@ -3341,7 +3344,7 @@ void CEXEBuild::set_uninstall_mode(int un)
 
     SWAP(db_opt_save_u,db_opt_save,UINT64);
     SWAP(db_comp_save_u,db_comp_save,int);
-    SWAP(db_full_size_u,db_full_size,unsigned int);
+    SWAP(db_full_size_u,db_full_size,UINT64);
   }
 }
 
diff --git a/Source/build.h b/Source/build.h
index c825876c..a11b5c44 100644
--- a/Source/build.h
+++ b/Source/build.h
@@ -465,9 +465,8 @@ class CEXEBuild {
 
     StringList m_macro_entry;
 
-    UINT64 db_opt_save, db_opt_save_u;
+    UINT64 db_opt_save, db_opt_save_u, db_full_size, db_full_size_u;
     int db_comp_save, db_comp_save_u;
-    unsigned int db_full_size, db_full_size_u;
 
     FastStringList include_dirs;
 
diff --git a/Source/util.cpp b/Source/util.cpp
index 01b4d501..d5864af5 100644
--- a/Source/util.cpp
+++ b/Source/util.cpp
@@ -85,17 +85,6 @@ unsigned int my_strncpy(TCHAR*Dest, const TCHAR*Src, unsigned int cchMax)
   return cch;
 }
 
-const TCHAR* GetFriendlySize(UINT64 n, unsigned int&fn, bool accurate)
-{
-  static const TCHAR* names[] = {
-    _T("bytes"), _T("KiB"), _T("MiB"), _T("GiB"), _T("TiB")
-  };
-  unsigned char s = 0;
-  while(n > ((!accurate || s) ? 1024-1 : UINT_MAX)) n /= 1024, ++s;
-  fn = (unsigned int) n;
-  return s >= COUNTOF(names) ? _T("?") : 1 == fn && !s ? _T("byte") : names[s];
-}
-
 // Returns 0 if everything is OK
 // Returns -1 if can't find the file
 // Returns -2 if the file is an invalid bitmap
@@ -819,6 +808,18 @@ size_t ExpandoStrFmtVaList(wchar_t*Stack, size_t cchStack, wchar_t**ppMalloc, co
   return cch;
 }
 
+const TCHAR* GetFriendlySize(UINT64 n, unsigned int&fn, GETFRIENDLYSIZEFLAGS f)
+{
+  static const TCHAR* scale[] = {
+    _T(" bytes"), _T(" KiB"), _T(" MiB"), _T(" GiB"), _T(" TiB")
+  };
+  unsigned char s = 0, accurate = f&GFSF_BYTESIFPOSSIBLE;
+  while(n > ((s || !accurate) ? (1024*1024)-1 : UINT_MAX)) n /= 1024, ++s;
+  fn = (unsigned int) n;
+  if (!s) return (f&GFSF_HIDEBYTESCALE) ? _T("") : 1 == fn ? _T(" byte") : scale[s];
+  return s >= COUNTOF(scale) ? _T(" ?") : scale[s];
+}
+
 #if defined(_WIN32) && defined(_UNICODE)
 int RunChildProcessRedirected(LPCWSTR cmdprefix, LPCWSTR cmdmain)
 {
diff --git a/Source/util.h b/Source/util.h
index 4abd80e1..2d44863c 100644
--- a/Source/util.h
+++ b/Source/util.h
@@ -35,7 +35,6 @@
 extern double my_wtof(const wchar_t *str);
 extern unsigned int my_strncpy(TCHAR*Dest, const TCHAR*Src, unsigned int cchMax);
 size_t my_strftime(TCHAR *s, size_t max, const TCHAR  *fmt, const struct tm *tm);
-const TCHAR* GetFriendlySize(UINT64 n, unsigned int&fn, bool accurate = false);
 
 // Adds the bitmap in filename using resource editor re as id id.
 // If width or height are specified it will also make sure the bitmap is in that size
@@ -78,6 +77,22 @@ public:
   operator T*() { return GetPtr(); }
 };
 
+typedef enum {
+  GFSF_BYTESIFPOSSIBLE = 0x1,
+  GFSF_HIDEBYTESCALE   = 0x2,
+  GFSF_DEFAULT = 0
+} GETFRIENDLYSIZEFLAGS;
+const TCHAR* GetFriendlySize(UINT64 n, unsigned int&fn, GETFRIENDLYSIZEFLAGS f = GFSF_DEFAULT);
+class FriendlySize {
+  const TCHAR* m_s;
+  unsigned int m_n;
+public:
+  FriendlySize(UINT64 n, size_t f = GFSF_DEFAULT) { Calculate(n, f); }
+  void Calculate(UINT64 n, size_t f) { m_s = GetFriendlySize(n, m_n, (GETFRIENDLYSIZEFLAGS)f); }
+  unsigned int UInt() const { return m_n; }
+  const TCHAR* Scale() const { return m_s; }
+};
+
 int sane_system(const TCHAR *command);
 
 void PrintColorFmtMsg(unsigned int type, const TCHAR *fmtstr, va_list args);