diff --git a/cmd/observability-proxy/main.go b/cmd/observability-proxy/main.go
index cce06e230..aa29d365f 100644
--- a/cmd/observability-proxy/main.go
+++ b/cmd/observability-proxy/main.go
@@ -102,6 +102,8 @@ func parseFlags(args []string) (options, error) {
 		return o, errors.New("--logs-default-limit must be positive and not above --logs-max-limit")
 	case o.logs.MaxTailResume < 0:
 		return o, errors.New("--logs-max-tail-resume must not be negative")
+	case o.requestTimeout < 0 || o.tailIdleTimeout < 0 || o.authCacheTTL < 0 || o.shutdownTimeout < 0:
+		return o, errors.New("timeouts and the auth cache TTL must not be negative")
 	}
 	return o, nil
 }
diff --git a/cmd/observability-proxy/main_test.go b/cmd/observability-proxy/main_test.go
index 52c147cf0..8fac1aa6d 100644
--- a/cmd/observability-proxy/main_test.go
+++ b/cmd/observability-proxy/main_test.go
@@ -53,6 +53,9 @@ func TestParseFlagsInvalid(t *testing.T) {
 		{"--logs-default-limit=0"},
 		{"--logs-default-limit=100", "--logs-max-limit=10"},
 		{"--logs-max-tail-resume=-1m"},
+		{"--request-timeout=-1s"},
+		{"--tail-idle-timeout=-1s"},
+		{"--auth-cache-ttl=-1s"},
 		{"--unknown"},
 	} {
 		if _, err := parseFlags(args); err == nil {