diff --git a/t/05-scheduler-full.t b/t/05-scheduler-full.t
index 7cd2c2205cd..47fce181ceb 100644
--- a/t/05-scheduler-full.t
+++ b/t/05-scheduler-full.t
@@ -45,6 +45,12 @@ plan skip_all => "set FULLSTACK=1 (be careful)" unless $ENV{FULLSTACK};
 setup_mojo_app_with_default_worker_timeout;
 OpenQA::Setup::read_config(OpenQA::App->singleton);
 
+# fake "/proc/loadavg" to ensure the test works under a heavy load
+my $load_avg_file = tempfile('worker-overall-load-avg-XXXXX');
+my $load_avg_file_realpath = $load_avg_file->realpath;
+$load_avg_file->spew('0.93 0.95 3.25 2/2207 1212');
+$ENV{OPENQA_LOAD_AVG_FILE} = $load_avg_file_realpath;
+
 # setup directories and database
 my $tempdir = setup_fullstack_temp_dir('scheduler');
 my $schema = OpenQA::Test::Database->new->create(fixtures_glob => '01-jobs.pl 02-workers.pl');
diff --git a/t/43-scheduling-and-worker-scalability.t b/t/43-scheduling-and-worker-scalability.t
index a97b4fa21e8..d5607813851 100644
--- a/t/43-scheduling-and-worker-scalability.t
+++ b/t/43-scheduling-and-worker-scalability.t
@@ -9,7 +9,7 @@ use Test::MockModule;
 use Time::HiRes 'sleep';
 use File::Path 'make_path';
 use Scalar::Util 'looks_like_number';
-use Mojo::File 'path';
+use Mojo::File qw(path tempfile);
 use Mojo::Util 'dumper';
 use IPC::Run qw(start);
 use FindBin;
@@ -41,6 +41,12 @@ BEGIN {
 setup_mojo_app_with_default_worker_timeout;
 OpenQA::Setup::read_config(OpenQA::App->singleton);
 
+# fake "/proc/loadavg" to ensure the test works under a heavy load
+my $load_avg_file = tempfile('worker-overall-load-avg-XXXXX');
+my $load_avg_file_realpath = $load_avg_file->realpath;
+$load_avg_file->spew('0.93 0.95 3.25 2/2207 1212');
+$ENV{OPENQA_LOAD_AVG_FILE} = $load_avg_file_realpath;
+
 # read number of workers to spawn from environment variable; skip test entirely if variable not present
 # similar to other fullstack tests
 my $worker_count = $ENV{SCALABILITY_TEST_WORKER_COUNT};