Fix call-with-duration-metric to work with multiple values

1 files changed, 6 insertions, 3 deletions

diff --git a/prometheus.scm b/prometheus.scm
index 0d44377..53859c5 100644
--- a/prometheus.scm
+++ b/prometheus.scm
@@ -355,9 +355,12 @@ The metric with the name @var{metric-name} is fetched from the
                registry
                metric-name)))
          (start-time (current-time)))
-    (let ((result (thunk)))
-      (metric-observe metric (- (current-time) start-time))
-      result)))
+    (call-with-values
+        thunk
+      (lambda results
+        (metric-observe metric (- (current-time) start-time))
+
+        (apply values results)))))
 
 (define (write-metrics registry port)
   "Write all metrics from the given @var{registry} to @var{port} in