diff --git a/core/application/watchdog.go b/core/application/watchdog.go
index c71871d87..330c95353 100644
--- a/core/application/watchdog.go
+++ b/core/application/watchdog.go
@@ -61,7 +61,15 @@ func extractModelGroupsFromConfigs(configs []config.ModelConfig) map[string][]st
 	return out
 }
 
+// StopWatchdog signals the watchdog to stop. It takes the watchdogMutex because
+// startWatchdog/RestartWatchdog reassign and close a.watchdogStop under that same
+// lock, and POST /api/settings can reach either this or RestartWatchdog depending
+// on WatchdogShouldRun(). Without the lock, two callers can both observe a non-nil
+// channel and close it twice, which panics.
 func (a *Application) StopWatchdog() error {
+	a.watchdogMutex.Lock()
+	defer a.watchdogMutex.Unlock()
+
 	if a.watchdogStop != nil {
 		close(a.watchdogStop)
 		a.watchdogStop = nil
diff --git a/core/application/watchdog_test.go b/core/application/watchdog_test.go
index ddb1a6849..09e856e10 100644
--- a/core/application/watchdog_test.go
+++ b/core/application/watchdog_test.go
@@ -1,6 +1,8 @@
 package application
 
 import (
+	"sync"
+
 	"github.com/mudler/LocalAI/core/config"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
@@ -45,3 +47,32 @@ var _ = Describe("extractModelGroupsFromConfigs", func() {
 		Expect(out).ToNot(HaveKey("a"))
 	})
 })
+
+var _ = Describe("StopWatchdog", func() {
+	It("closes the stop channel exactly once under concurrent callers", func() {
+		// POST /api/settings routes to StopWatchdog whenever the new settings make
+		// WatchdogShouldRun() false, so concurrent requests land here in parallel.
+		// Before the mutex was taken, both could observe a non-nil watchdogStop and
+		// close it twice, panicking with "close of closed channel".
+		app := &Application{watchdogStop: make(chan bool, 1)}
+
+		var wg sync.WaitGroup
+		for i := 0; i < 64; i++ {
+			wg.Add(1)
+			go func() {
+				defer GinkgoRecover()
+				defer wg.Done()
+				Expect(app.StopWatchdog()).To(Succeed())
+			}()
+		}
+		wg.Wait()
+
+		Expect(app.watchdogStop).To(BeNil())
+	})
+
+	It("is a no-op when the watchdog was never started", func() {
+		app := &Application{}
+		Expect(app.StopWatchdog()).To(Succeed())
+		Expect(app.watchdogStop).To(BeNil())
+	})
+})