diff --git a/mamba/cli.py b/mamba/cli.py
index <HASH>..<HASH> 100644
--- a/mamba/cli.py
+++ b/mamba/cli.py
@@ -17,6 +17,9 @@ def main():
 
     formatter.format_summary()
 
+    if runner.has_failed_tests:
+        sys.exit(1)
+
 
 if __name__ == '__main__':
     main()
diff --git a/mamba/runner.py b/mamba/runner.py
index <HASH>..<HASH> 100644
--- a/mamba/runner.py
+++ b/mamba/runner.py
@@ -2,8 +2,11 @@ class Runner(object):
 
     def __init__(self, formatter):
         self.formatter = formatter
+        self.has_failed_tests = False
 
     def run(self, module):
         for spec in module.specs:
             spec.run()
             self.formatter.format(spec)
+            if spec.failed:
+                self.has_failed_tests = True
If an error was happened in execution exit with 1 error code