diff --git a/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test.cc b/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test.cc
index ee8d9d196..69893257b 100644
--- a/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test.cc
+++ b/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test.cc
@@ -543,7 +543,7 @@ bool HybridObservablesTest::acquire_signal()
 #if USE_GLOG_AND_GFLAGS
     config->set_property("Acquisition.threshold", std::to_string(FLAGS_external_signal_acquisition_threshold));
 #else
-    config->set_property("Acquisition.threshold", absl::GetFlag(FLAGS_external_signal_acquisition_threshold));
+    config->set_property("Acquisition.threshold", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_threshold)));
 #endif
 
     acquisition->set_gnss_synchro(&tmp_gnss_synchro);
diff --git a/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test_fpga.cc b/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test_fpga.cc
index 49809e4b3..1d0e04225 100644
--- a/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test_fpga.cc
+++ b/tests/unit-tests/signal-processing-blocks/observables/hybrid_observables_test_fpga.cc
@@ -902,7 +902,7 @@ void HybridObservablesTestFpga::configure_receiver(
 #if USE_GLOG_AND_GFLAGS
     config->set_property("Acquisition.threshold", std::to_string(FLAGS_external_signal_acquisition_threshold));
 #else
-    config->set_property("Acquisition.threshold", absl::GetFlag(FLAGS_external_signal_acquisition_threshold));
+    config->set_property("Acquisition.threshold", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_threshold)));
 #endif
 
     std::string System_and_Signal;
diff --git a/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test.cc b/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test.cc
index eca2c661c..3183af17b 100644
--- a/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test.cc
+++ b/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test.cc
@@ -327,7 +327,7 @@ void TrackingPullInTest::configure_receiver(
 #if USE_GLOG_AND_GFLAGS
     config->set_property("Acquisition.threshold", std::to_string(FLAGS_external_signal_acquisition_threshold));
 #else
-    config->set_property("Acquisition.threshold", absl::GetFlag(FLAGS_external_signal_acquisition_threshold));
+    config->set_property("Acquisition.threshold", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_threshold)));
 #endif
 
     std::string System_and_Signal;
diff --git a/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test_fpga.cc b/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test_fpga.cc
index def596542..69aab747c 100644
--- a/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test_fpga.cc
+++ b/tests/unit-tests/signal-processing-blocks/tracking/tracking_pull-in_test_fpga.cc
@@ -538,7 +538,7 @@ void TrackingPullInTestFpga::configure_receiver(
 #if USE_GLOG_AND_GFLAGS
     config->set_property("Acquisition.threshold", std::to_string(FLAGS_external_signal_acquisition_threshold));
 #else
-    config->set_property("Acquisition.threshold", absl::GetFlag(FLAGS_external_signal_acquisition_threshold));
+    config->set_property("Acquisition.threshold", std::to_string(absl::GetFlag(FLAGS_external_signal_acquisition_threshold)));
 #endif
 
     std::string System_and_Signal;