diff --git a/src/clause_types.rs b/src/clause_types.rs
index 09cab2bb..89e4d00d 100644
--- a/src/clause_types.rs
+++ b/src/clause_types.rs
@@ -176,6 +176,8 @@ pub enum SystemClauseType {
     FileExists,
     DirectoryExists,
     MakeDirectory,
+    DeleteFile,
+    WorkingDirectory,
     DeleteAttribute,
     DeleteHeadAttribute,
     DynamicModuleResolution(usize),
@@ -341,6 +343,8 @@ impl SystemClauseType {
             &SystemClauseType::FileExists => clause_name!("$file_exists"),
             &SystemClauseType::DirectoryExists => clause_name!("$directory_exists"),
             &SystemClauseType::MakeDirectory => clause_name!("$make_directory"),
+            &SystemClauseType::DeleteFile => clause_name!("$delete_file"),
+            &SystemClauseType::WorkingDirectory => clause_name!("$working_directory"),
             &SystemClauseType::REPL(REPLCodePtr::CompileBatch) => clause_name!("$compile_batch"),
             &SystemClauseType::REPL(REPLCodePtr::UseModule) => clause_name!("$use_module"),
             &SystemClauseType::REPL(REPLCodePtr::UseQualifiedModule) => {
@@ -675,6 +679,8 @@ impl SystemClauseType {
             ("$file_exists", 1) => Some(SystemClauseType::FileExists),
             ("$directory_exists", 1) => Some(SystemClauseType::DirectoryExists),
             ("$make_directory", 1) => Some(SystemClauseType::MakeDirectory),
+            ("$delete_file", 1) => Some(SystemClauseType::DeleteFile),
+            ("$working_directory", 2) => Some(SystemClauseType::WorkingDirectory),
             ("$use_module", 1) => Some(SystemClauseType::REPL(REPLCodePtr::UseModule)),
             ("$use_module_from_file", 1) =>
                     Some(SystemClauseType::REPL(REPLCodePtr::UseModuleFromFile)),
diff --git a/src/lib/files.pl b/src/lib/files.pl
index b53b9bbb..9e54bf33 100644
--- a/src/lib/files.pl
+++ b/src/lib/files.pl
@@ -50,7 +50,9 @@
                   file_size/2,
                   file_exists/1,
                   directory_exists/1,
-                  make_directory/1]).
+                  delete_file/1,
+                  make_directory/1,
+                  working_directory/2]).
 
 :- use_module(library(error)).
 :- use_module(library(lists)).
@@ -80,3 +82,12 @@ directory_exists(Directory) :-
 make_directory(Directory) :-
         list_of_chars(Directory),
         '$make_directory'(Directory).
+
+delete_file(File) :-
+        list_of_chars(File),
+        '$delete_file'(File).
+
+working_directory(Dir0, Dir) :-
+        can_be(list, Dir0),
+        can_be(list, Dir),
+        '$working_directory'(Dir0, Dir).
diff --git a/src/machine/system_calls.rs b/src/machine/system_calls.rs
index 20bf70e4..77ef1366 100644
--- a/src/machine/system_calls.rs
+++ b/src/machine/system_calls.rs
@@ -880,6 +880,44 @@ impl MachineState {
                     }
                 }
             }
+            &SystemClauseType::DeleteFile => {
+                let file = self.heap_pstr_iter(self[temp_v!(1)]).to_string();
+
+                match fs::remove_file(file) {
+                    Ok(_) => { }
+                    _ => { self.fail = true;
+                           return Ok(());
+                    }
+                }
+            }
+            &SystemClauseType::WorkingDirectory => {
+                if let Ok(dir) = env::current_dir() {
+                    let current =
+                        match dir.to_str() {
+                            Some(d) => { d }
+                            _ => { let stub = MachineError::functor_stub(clause_name!("working_directory"), 2);
+                                   let err = MachineError::representation_error(RepFlag::Character);
+                                   let err = self.error_form(err, stub);
+
+                                   return Err(err);
+                            }
+                        };
+                    let chars = self.heap.put_complete_string(current);
+                    self.unify(self[temp_v!(1)], chars);
+
+                    let next = self.heap_pstr_iter(self[temp_v!(2)]).to_string();
+
+                    match env::set_current_dir(std::path::Path::new(&next)) {
+                        Ok(_) => { }
+                        _ => { self.fail = true;
+                               return Ok(());
+                        }
+                    }
+                } else {
+                    self.fail = true;
+                    return Ok(());
+                }
+            }
             &SystemClauseType::AtEndOfExpansion => {
                 if self.cp == LocalCodePtr::TopLevel(0, 0) {
                     self.at_end_of_expansion = true;