diff --git a/lblprof/custom_sysmon.py b/lblprof/custom_sysmon.py
index 243ad4b..2423c3d 100644
--- a/lblprof/custom_sysmon.py
+++ b/lblprof/custom_sysmon.py
@@ -168,7 +168,14 @@ def _handle_return(self, code, instruction_offset, retval):
     def start_tracing(self) -> None:
         # Reset state
         self.__init__()
-        sys.monitoring.use_tool_id(self.tool_id, "lblprof-monitor")
+        if not sys.monitoring.get_tool(self.tool_id):
+            sys.monitoring.use_tool_id(self.tool_id, "lblprof-monitor")
+        else:
+            # if the tool already assigned is not ours, we need to raise an error
+            if sys.monitoring.get_tool(self.tool_id) != "lblprof-monitor":
+                raise RuntimeError(
+                    "A tool with the id lblprof-monitor is already assigned, please stop it before starting a new tracing"
+                )
 
         # Register our callback functions
         sys.monitoring.register_callback(
diff --git a/pyproject.toml b/pyproject.toml
index f2ab3f0..9a52a05 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "lblprof"
-version = "0.1.7"
+version = "0.1.8"
 description = "Line by line terminal based profiler"
 authors = [
   { name="le-codeur-rapide", email="paul.vezia@gmail.com" }