diff --git a/tupak/gw/detector.py b/tupak/gw/detector.py
index 364eaa4725338aae0720ca157a4b5e452112a456..83f74aa020f0f16abb1fb8c8d8fdc5c13d96912e 100644
--- a/tupak/gw/detector.py
+++ b/tupak/gw/detector.py
@@ -1256,7 +1256,7 @@ class Interferometer(object):
         if not self.strain_data.time_within_data(parameters['geocent_time']):
             logger.warning(
                 'Injecting signal outside segment, start_time={}, merger time={}.'
-                    .format(self.strain_data.start_time, parameters['geocent_time']))
+                .format(self.strain_data.start_time, parameters['geocent_time']))
 
         signal_ifo = self.get_detector_response(injection_polarizations, parameters)
         if np.shape(self.frequency_domain_strain).__eq__(np.shape(signal_ifo)):