diff --git a/modules/services/borgmatic.nix b/modules/services/borgmatic.nix
index f91e84cd0..f5368cdfc 100644
--- a/modules/services/borgmatic.nix
+++ b/modules/services/borgmatic.nix
@@ -58,7 +58,7 @@ in {
           LogRateLimitIntervalSec = 0;
 
           # Delay start to prevent backups running during boot:
-          ExecStartPre = "sleep 3m";
+          ExecStartPre = "${pkgs.coreutils}/bin/sleep 3m";
 
           ExecStart = ''
             ${pkgs.systemd}/bin/systemd-inhibit \
diff --git a/tests/modules/services/borgmatic/basic-configuration.service b/tests/modules/services/borgmatic/basic-configuration.service
index 6101b2b66..4840f11bc 100644
--- a/tests/modules/services/borgmatic/basic-configuration.service
+++ b/tests/modules/services/borgmatic/basic-configuration.service
@@ -9,7 +9,7 @@ ExecStart=/nix/store/00000000000000000000000000000000-systemd/bin/systemd-inhibi
     --list \
     --syslog-verbosity 1
 
-ExecStartPre=sleep 3m
+ExecStartPre=/nix/store/00000000000000000000000000000000-coreutils/bin/sleep 3m
 IOSchedulingClass=best-effort
 IOSchedulingPriority=7
 IOWeight=100