*** Source/cmAddSubDirectoryCommand.cxx
--- Source/cmAddSubDirectoryCommand.cxx_fixed
***************
*** 92,104 ****
        }
  
      // Remove the CurrentDirectory from the srcPath and replace it
      // with the CurrentOutputDirectory.
      binPath = srcPath;
      cmSystemTools::ReplaceString(binPath,
!                                  this->Makefile->GetCurrentDirectory(),
                                   this->Makefile->GetCurrentOutputDirectory());
      }
    else
      {
      // Use the binary directory specified.
      // Interpret a relative path with respect to the current binary directory.
--- 92,112 ----
        }
  
      // Remove the CurrentDirectory from the srcPath and replace it
      // with the CurrentOutputDirectory.
      binPath = srcPath;
  
+     std::string currentDir = this->Makefile->GetCurrentDirectory();
+     if(!currentDir.empty() && currentDir[currentDir.length() - 1] == '/')
+     {
+         // we must be on Windows in the root directory of a drive - we must avoid replacing the trailing slash
+         currentDir.erase(currentDir.length() - 1);
+     }
  
      cmSystemTools::ReplaceString(binPath,
!                                  currentDir.c_str(),
                                   this->Makefile->GetCurrentOutputDirectory());
      }
    else
      {
      // Use the binary directory specified.
      // Interpret a relative path with respect to the current binary directory.