diff --git a/dragon_runner/runner.py b/dragon_runner/runner.py
index 0642900..0e959ca 100644
--- a/dragon_runner/runner.py
+++ b/dragon_runner/runner.py
@@ -15,7 +15,8 @@
 from dragon_runner.toolchain    import Step
 from dragon_runner.cli          import CLIArgs
 from dragon_runner.utils        import make_tmp_file, bytes_to_str,\
-                                       file_to_bytes, truncated_bytes
+                                       file_to_bytes, truncated_bytes, \
+                                       set_timeout
 
 init(autoreset=True)
 
@@ -218,7 +219,6 @@ def run(self, test: TestFile, exe: Executable) -> Optional[TestResult]:
                 """
                 timeout_msg = f"Toolchain timed out for test: {test.file}"
                 tr.did_pass=False;
-                # tr.did_panic=True;
                 tr.failing_step=step.name;
                 tr.error_msg=timeout_msg;
                 return tr
@@ -244,9 +244,14 @@ def run(self, test: TestFile, exe: Executable) -> Optional[TestResult]:
                         error_pattern = r'.*?(Error on line \d+):?.*' 
                     else:
                         error_pattern = r'\s*(\w+Error):?.*'
-                    if lenient_diff(step_stderr, expected, error_pattern) == "":
-                        tr.did_pass = True
-                    else:
+                    
+                    # Check if diffs timeout eventually on massive stderrr dumps
+                    try:
+                        if lenient_diff(step_stderr, expected, error_pattern) == "":
+                            tr.did_pass = True
+                        else:
+                            tr.did_pass = False
+                    except TimeoutError:
                         tr.did_pass = False
                 return tr;
 
@@ -352,12 +357,13 @@ def precise_diff(produced: bytes, expected: bytes) -> str:
         return ""
     return diff_bytes(produced, expected)
 
+@set_timeout(timeout=5)
 def lenient_diff(produced: bytes, expected: bytes, pattern: str) -> str:
     """
     Perform a lenient diff on error messages, using the pattern as a mask/filter.
     Unfortunately we have to convert from and back to bytes in order to apply regex.
     Bytes must be UTF-8 decodable.
-    """  
+    """
     produced_str = p.strip() if (p := bytes_to_str(produced)) else None
     expected_str = e.strip() if (e := bytes_to_str(expected)) else None
     
diff --git a/dragon_runner/utils.py b/dragon_runner/utils.py
index 804edeb..3f131d7 100644
--- a/dragon_runner/utils.py
+++ b/dragon_runner/utils.py
@@ -1,9 +1,9 @@
 import os
 import sys
+import multiprocessing
 import tempfile
 from typing     import Optional
 from colorama   import init
-
 # Initialize colorama
 init(autoreset=True)
 
@@ -111,3 +111,25 @@ def bytes_to_file(file: str, data: bytes) -> Optional[str]:
         print(f"Writting bytes to file failed with: {e}")
         return None
 
+def set_timeout(timeout):
+    """
+    Decorator to make a function throw a timeout error if it is taking too
+    long to execute.
+    """
+    def decorator(func):
+        def wrapper(*args, **kwargs):
+            result = multiprocessing.Queue()
+            process = multiprocessing.Process(
+                    target=lambda q: q.put(func(*args, **kwargs)), args=(result,))
+            process.start()
+            process.join(timeout)
+            if process.is_alive():
+                process.terminate()
+                raise TimeoutError(f"Function '{func.__name__}' timed out after {timeout} seconds")
+            outcome = result.get()
+            if isinstance(outcome, Exception):
+                raise outcome
+            return outcome
+        return wrapper
+    return decorator
+
diff --git a/tests/conftest.py b/tests/conftest.py
index 3a5ca3e..21465b1 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -18,7 +18,7 @@ def create_cli_args(**kwargs) -> CLIArgs:
         failure_log     = kwargs.get('failure_log', None),
         debug_package   = kwargs.get('debug_package', None),
         mode            = kwargs.get('mode', None),
-        timeout         = kwargs.get('timeout', None),
+        timeout         = kwargs.get('timeout', 5),
         time            = kwargs.get('time', None),
         verbosity       = kwargs.get('verbosity', None),
         verify          = kwargs.get('verify', None),