--- main.cc~	2017-03-16 18:44:50.000000000 +0100
+++ main.cc	2017-12-11 13:13:14.000000000 +0100
@@ -678,7 +678,16 @@
       std::max( data_size, LZ_min_dictionary_size() );
 
   if( num_workers <= 0 )
+    {
+    if( sizeof (void *) <= 4 )	// use less than 2 GiB on 32 bit systems
+      {
+      const long long mem =
+        11LL * encoder_options.dictionary_size + 3LL * data_size;
+      const int nmax32 = ( 0x7FFFFFFF > mem ) ? 0x7FFFFFFF / mem : 1;
+      if( max_workers > nmax32 ) max_workers = nmax32;
+      }
     num_workers = std::min( num_online, max_workers );
+    }
 
   if( !to_stdout && program_mode != m_test &&
       ( filenames_given || default_output_filename.size() ) )