diff --git a/gstlal-burst/gst/lal/gstlal_string_triggergen.c b/gstlal-burst/gst/lal/gstlal_string_triggergen.c
index 04d908c51ca3c1107e3f6819720544e052ee41bf..12dff5ec7ed93e03dc3d8769ac22d70b06707437 100644
--- a/gstlal-burst/gst/lal/gstlal_string_triggergen.c
+++ b/gstlal-burst/gst/lal/gstlal_string_triggergen.c
@@ -101,13 +101,13 @@ G_DEFINE_TYPE_WITH_CODE(
 
 static unsigned autocorrelation_channels(const gsl_matrix_float *autocorrelation_matrix)
 {
-	return autocorrelation_matrix->size1;
+	return autocorrelation_matrix ? autocorrelation_matrix->size1 : 0;
 }
 
 
 static unsigned autocorrelation_length(const gsl_matrix_float *autocorrelation_matrix)
 {
-	return autocorrelation_matrix->size2;
+	return autocorrelation_matrix ? autocorrelation_matrix->size2 : 0;
 }