diff --git a/guile/list-gitlab-merge-requests.scm b/guile/list-gitlab-merge-requests.scm
index b93641e..5dbebe7 100644
--- a/guile/list-gitlab-merge-requests.scm
+++ b/guile/list-gitlab-merge-requests.scm
@@ -2,9 +2,9 @@
 --no-auto-compile -e main -s
 !#
 
-(use-modules (ice-9 exceptions)
+(use-modules (ice-9 binary-ports)
+             (ice-9 exceptions)
              (ice-9 match)
-             (ice-9 textual-ports)
              (json)
              (srfi srfi-1)
              (srfi srfi-26)
@@ -13,10 +13,12 @@
              (web response)
              (web uri))
 
-(define gitlab-token (string-trim-right (getenv "GITLAB_TOKEN")))
+(define gitlab-token (string-trim (getenv "GITLAB_TOKEN")))
 (define base-url "https://gitlab.com/api/v4")
 
 (define (encode-query alist)
+  "Encode an association list as a query string. The keys should be symbols and the
+values strings or #f, in which case the parameter is skipped."
   (fold (match-lambda*
           (((k . v) s)
            (if v
@@ -32,10 +34,6 @@
 (define (json-response? res)
   (eq? 'application/json (car (response-content-type res))))
 
-(define (text-response? res)
-  (string-prefix? "text/"
-                  (symbol->string (car (response-content-type res)))))
-
 (define (json-ok? res)
   (and (= 200 (response-code res))
        (json-response? res)))
@@ -47,28 +45,20 @@
   (status-code api-error-status-code)
   (body api-error-body))
 
-(define-syntax check-api-response
-  (syntax-rules ()
-    ((check-api-response endpoint res body-port)
-     (check-api-response endpoint res body-port (<= 100 (response-code res) 399)))
-    ((check-api-response endpoint res body-port ok?)
-     (unless ok?
-       (let ((body (cond
-                    ((json-response? res) (json->scm body-port))
-                    ((text-response? res) (get-string-all body-port))
-                    (else "<binary response body>"))))
-         (close-port body-port)
-         (raise-exception (make-api-error endpoint (response-code res) body)))))))
-
+(define* (api-call method endpoint #:key query payload (ok? json-ok?) (post-proc identity))
+  (let* ((res body (method (if query
+                               (string-append base-url endpoint "?" (encode-query query))
+                               (string-append base-url endpoint))
+                           #:headers `((private-token . ,gitlab-token)
+                                       (content-type . (application/json (charset . "utf-8"))))
+                           #:body (if payload (scm->json payload) #f)))
+         (body (if (json-response? res) (call-with-input-bytevector body json->scm) body)))
+    (if (ok? res)
+        (post-proc body)
+        (raise-exception (make-api-error endpoint (response-code res) body)))))
 
 (define (list-merge-requests params)
-  (let ((res body-port (http-get (string-append base-url "/merge_requests?" (encode-query params))
-                                 #:headers `((private-token . ,gitlab-token))
-                                 #:streaming? #t)))
-    (check-api-response "list-merge-requests" res body-port json-ok?)
-    (let ((body (json->scm body-port)))
-      (close-port body-port)
-      (vector->list body))))
+  (api-call http-get "/merge_requests" #:query params #:post-proc vector->list))
 
 (define (field-equal? field-name value)
   (lambda (alist)