diff --git a/Source/cmFileCommand.cxx b/Source/cmFileCommand.cxx
index 447e75e15..9f8523c3b 100644
--- a/Source/cmFileCommand.cxx
+++ b/Source/cmFileCommand.cxx
@@ -231,7 +231,7 @@ bool cmFileCommand::HandleReadCommand(std::vector<std::string> const& args)
     {
     if (sizeLimit > 0)
       {
-      sizeLimit -= line.size();
+      sizeLimit = sizeLimit - static_cast<long>(line.size());
       if (has_newline)
         {
         sizeLimit--;
diff --git a/Source/kwsys/SystemTools.cxx b/Source/kwsys/SystemTools.cxx
index ec7f96f33..9892d7348 100644
--- a/Source/kwsys/SystemTools.cxx
+++ b/Source/kwsys/SystemTools.cxx
@@ -3589,13 +3589,13 @@ bool SystemTools::GetLineFromStream(kwsys_ios::istream& is,
         }
       else
         {
-        leftToRead -= length;
+        leftToRead -= static_cast<long>(length);
         }
       }
 
     // Append the data read to the line.
     line.append(buffer);
-    sizeLimit -= length;
+    sizeLimit = sizeLimit - static_cast<long>(length);
     }
 
   // Return the results.