--- a/rakelib/test.rake	Sun Nov 20 23:28:58 2016 +0000
+++ b/rakelib/test.rake	Mon Nov 21 23:00:19 2016 +0000
@@ -55,6 +55,13 @@
   coveragerportformat_dot_st = BUILD_DIR / 'stx' / 'goodies' / 'builder' / 'reports' / 'Builder__CoverageReportFormat.st'
 
   report_dir = File.expand_path(REPORT_DIR)
+  tmp_dir = File.expand_path(TMP_DIR)
+  
+  # Set STX_TMPDIR environment to make sure all temporary files created by 
+  # Smalltalk/X goes to a local tmp directory (which should be discarded 
+  # regularly). This helps to avoid garbage to heap up on Windows slaves 
+  # assuming workspaces is thrown away often.
+  ENV['STX_TMPDIR'] = tmp_dir
 
   if app
     exe_dir = BUILD_DIR / app.directory
@@ -72,6 +79,9 @@
     end
   end
 
+  if not File.directory? tmp_dir then
+    mkdir_p tmp_dir
+  end
   chdir exe_dir do
     packages_args = ''
     packages.each { | p | packages_args += " -p #{p}" }
@@ -83,6 +93,7 @@
     end    
     sh "#{exe} #{runner_opts} #{global_opts} -i \"#{BUILD_ID}\" -D \"#{report_dir}\" -r #{report} #{report_opts} #{packages_args}"
   end
+  rm_rf tmp_dir
 end
 
 task :'setup:tasks:test' do