diff --git a/README.md b/README.md
index cc59fb2..9bd0296 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,8 @@ The advantages of this tool are :
 
 * hash system to avoid time check issues (same file content, remote files problems, etc)
 
+* watch option to recompile whenever a source is changed
+
 
 ## Use
 
@@ -25,15 +27,14 @@ This repository is meant to be used as a submodule of a C/C++ project.
 
 By default 3 targets can be used `make` (or `make all` as usual default of makefiles), `make debug` and `make clean`.
 
-**Be careful** : `clean` will delete the object and binary output directories defined in `make.py`.
-
-
 **Example :** from the root folder of a project :
 
 ```
 git submodule add https://gitlab.com/corentin-pro/umake.git && cp umake/make* .
 ```
 
+Then change the configuration in `make.py` and a simple `make` command will build your project!
+
 
 ## How it works
 
diff --git a/umake.py b/umake.py
index ba5cafe..a2bf31f 100755
--- a/umake.py
+++ b/umake.py
@@ -128,18 +128,18 @@ class Builder:
 
     def make(self):
         self._populate_todo_dict()
-        self._compile_sources()
 
         if self._config.WATCH:
             from watch import Watcher, WatchFlag  # pylint: disable=import-outside-toplevel
 
             def callback(path: Path, _flags: WatchFlag):
                 source_hash = get_hash(path)
-                if source_hash != self._hash_dict[str(path)]:
+                if str(path) not in self._hash_dict or source_hash != self._hash_dict[str(path)]:
                     print(f'{ConsoleColor.ORANGE}Source file changed : {path} {ConsoleColor.ENDCOLOR}')
                     self._populate_todo_dict()
                     self._compile_sources()
 
+            self._compile_sources()
             watcher = Watcher()
             for source_path in self._compile_dict:
                 watcher.register(source_path, WatchFlag.MODIFY, callback)
@@ -147,6 +147,8 @@ class Builder:
                 watcher.watch()
             except KeyboardInterrupt:
                 print('\rExit')
+        elif not self._compile_sources():
+            sys.exit(1)
 
     def _populate_todo_dict(self):
         """Check source file and generate compilation commands to execute."""
@@ -170,12 +172,12 @@ class Builder:
         return ' '.join([self._config.CC, self._config.COMMON_FLAGS, self._config.COMPILE_FLAGS,
                         str(source_path), '-c', '-o', str(object_path)])
 
-    def _compile_sources(self):
+    def _compile_sources(self) -> bool:
         if not self._todo_dict and all(
                 (self._config.BIN_DIR / app_path).exists()
                 for app_path in self._config.APPS if app_path not in self._config.IGNORE_APPS):
             print(f'{ConsoleColor.GREEN}Nothing to do{ConsoleColor.ENDCOLOR}')
-            return
+            return True
 
         # Running compilation processes
         if not os.path.exists(self._config.OBJECT_DIR):
@@ -194,11 +196,13 @@ class Builder:
                     oldest_job.wait()
                     if oldest_job.returncode != 0:
                         error_paths.append((job_path, oldest_job.stdout.read() + oldest_job.stderr.read()))
+                        if str(job_path) in self._hash_dict:
+                            del self._hash_dict[str(job_path)]
                         break
                     # Update hash if no error
                     for dependency_path in self._dependency_dict[str(job_path)]:
                         self._hash_dict[str(dependency_path)] = get_hash(dependency_path)
-                    completed_paths.append(source_path)
+                    completed_paths.append(job_path)
             for source_path in completed_paths:
                 del self._todo_dict[source_path]
 
@@ -206,6 +210,8 @@ class Builder:
                 job.wait()
                 if job.returncode != 0:
                     error_paths.append((job_path, job.stdout.read() + job.stderr.read()))
+                    if str(job_path) in self._hash_dict:
+                        del self._hash_dict[str(job_path)]
                 else:
                     # Update hash if no error
                     for dependency_path in self._dependency_dict[str(job_path)]:
@@ -219,6 +225,8 @@ class Builder:
                                      universal_newlines=True, shell=True)
                 if job.returncode != 0:
                     error_paths.append((source_path, job.stdout + job.stderr))
+                    if str(source_path) in self._hash_dict:
+                        del self._hash_dict[str(source_path)]
                     break
                 # Update hash if no error
                 for dependency_path in self._dependency_dict[str(source_path)]:
@@ -232,7 +240,7 @@ class Builder:
                 print(ConsoleColor.RED + f'Error compiling {error_path}:\n' + ConsoleColor.ENDCOLOR + error_text)
             with open(self._config.OBJECT_DIR / 'hash.json', 'w', encoding='utf-8') as hash_file:
                 hash_file.write(json.dumps(self._hash_dict, indent=1))
-            sys.exit(1)
+            return False
 
         # Running linking processes
         if not self._config.BIN_DIR.exists():
@@ -288,9 +296,10 @@ class Builder:
                 print(ConsoleColor.RED + f'Error linking {error_path}:\n' + ConsoleColor.ENDCOLOR + error_text)
             with open(os.path.join(self._config.OBJECT_DIR, 'hash.json'), 'w', encoding='utf-8') as hash_file:
                 hash_file.write(json.dumps(self._hash_dict, indent=1))
-            sys.exit(1)
+            return False
 
         with open(self._config.OBJECT_DIR / 'hash.json', 'w', encoding='utf-8') as hash_file:
             hash_file.write(json.dumps(self._hash_dict, indent=1))
 
         print(f'{ConsoleColor.GREEN}Compilation done{ConsoleColor.ENDCOLOR}')
+        return True