diff --git a/Source/CPack/cmCPackTGZGenerator.cxx b/Source/CPack/cmCPackTGZGenerator.cxx
index 4d5c47034..22d6de365 100644
--- a/Source/CPack/cmCPackTGZGenerator.cxx
+++ b/Source/CPack/cmCPackTGZGenerator.cxx
@@ -129,7 +129,7 @@ ssize_t cmCPackTGZ_Data_Write(void *client_data, void *buff, size_t n)
 
   if ( mydata->Compress )
     {
-    mydata->ZLibStream.avail_in = n;
+    mydata->ZLibStream.avail_in = static_cast<uInt>(n);
     mydata->ZLibStream.next_in  = reinterpret_cast<Bytef*>(buff);
 
     do {
@@ -157,7 +157,8 @@ ssize_t cmCPackTGZ_Data_Write(void *client_data, void *buff, size_t n)
       }
     if ( n )
       {
-      mydata->CRC = crc32(mydata->CRC, reinterpret_cast<Bytef *>(buff), n);
+      mydata->CRC = crc32(mydata->CRC, reinterpret_cast<Bytef *>(buff), 
+                          static_cast<uInt>(n));
       }
     }
   else
diff --git a/Source/cmGeneratedFileStream.cxx b/Source/cmGeneratedFileStream.cxx
index 82ac2b778..660d9d5ef 100644
--- a/Source/cmGeneratedFileStream.cxx
+++ b/Source/cmGeneratedFileStream.cxx
@@ -228,7 +228,7 @@ int cmGeneratedFileStreamBase::CompressFile(const char* oldname,
   char buffer[BUFFER_SIZE];
   while ( (res = fread(buffer, 1, BUFFER_SIZE, ifs)) > 0 )
     {
-    if ( !gzwrite(gf, buffer, res) )
+    if ( !gzwrite(gf, buffer, static_cast<int>(res)) )
       {
       fclose(ifs);
       gzclose(gf);
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx
index 2f5bb5b1c..04d688585 100644
--- a/Source/cmSystemTools.cxx
+++ b/Source/cmSystemTools.cxx
@@ -1661,7 +1661,7 @@ ssize_t cmSystemToolsGZStructWrite(void* call_data, const void* buf,
                                    size_t count)
 {
   cmSystemToolsGZStruct* gzf = static_cast<cmSystemToolsGZStruct*>(call_data);
-  return gzwrite(gzf->GZFile, (void*)buf, count);
+  return gzwrite(gzf->GZFile, (void*)buf, static_cast<int>(count));
 }
 
 #endif
diff --git a/Utilities/cmtar/libtar.c b/Utilities/cmtar/libtar.c
index e9a14d8de..b50934935 100644
--- a/Utilities/cmtar/libtar.c
+++ b/Utilities/cmtar/libtar.c
@@ -130,13 +130,13 @@ static int libtar_gzclose(void* call_data)
 static ssize_t libtar_gzread(void* call_data, void* buf, size_t count)
 {
   struct gzStruct* gzf = (struct gzStruct*)call_data;
-  return gzread(gzf->GZFile, buf, count);
+  return gzread(gzf->GZFile, buf, (unsigned int)count);
 }
 
 static ssize_t libtar_gzwrite(void* call_data, const void* buf, size_t count)
 {
   struct gzStruct* gzf = (struct gzStruct*)call_data;
-  return gzwrite(gzf->GZFile, (void*)buf, count);
+  return gzwrite(gzf->GZFile, (void*)buf, (unsigned int)count);
 }
 
 tartype_t gztype = {