diff --git a/info.rkt b/info.rkt
index a7ae1ed..9cdb536 100644
--- a/info.rkt
+++ b/info.rkt
@@ -2,7 +2,7 @@
 
 (define collection "git")
 (define pkg-desc "Command-line-like Git operations for Racket, implemented with libgit2")
-(define version "0.2.6")
+(define version "0.2.7")
 (define pkg-authors '("Hans Dijkema"))
 (define license 'MIT)
 
diff --git a/main.rkt b/main.rkt
index c080838..bc692ea 100644
--- a/main.rkt
+++ b/main.rkt
@@ -8,7 +8,7 @@
          "credentials.rkt"
          libgit2)
 
-; gewijzigd. Nog een keer. 
+; Again.
 
 (provide git
          dgit
@@ -146,12 +146,14 @@
      0))
   callbacks)
 
-(define (set-push-progress-callback! callbacks label quiet)
-  (define report (make-progress-reporter label quiet #:bytes? #f))
+(define (set-push-progress-callback! callbacks _label _quiet)
+  ;; Diagnostic 0.2.7a: keep the libgit2 push progress callback installed,
+  ;; but do no Racket I/O (or other synchronization) from callback context.
+  ;; Racket CS runs FFI callbacks in atomic mode; writing to DrRacket's output
+  ;; port from here can therefore crash the process during a real push.
   (set-git_remote_callbacks-push_transfer_progress!
    callbacks
-   (lambda (current total bytes _payload)
-     (report current total bytes)
+   (lambda (_current _total _bytes _payload)
      0))
   callbacks)
 
diff --git a/scribblings/git.scrbl b/scribblings/git.scrbl
index 611162b..e42a670 100644
--- a/scribblings/git.scrbl
+++ b/scribblings/git.scrbl
@@ -109,9 +109,9 @@ Calls @racket[git], displays its result in a compact human-readable form, and re
 
 @defproc[(git-pull [remote string? "origin"] [#:quiet quiet any/c #f]) (or/c string? #f)]{Fetches and performs a fast-forward-only update of the current branch. Returns the new OID, or @racket[#f] when already up to date. A non-fast-forward update raises an exception.}
 
-@defproc[(git-push [remote string? "origin"] [branch (or/c string? #f) #f] [#:quiet quiet any/c #f]) void?]{Pushes a branch to a branch with the same name. With no positional arguments, the current branch is pushed to @tt{origin}; with only @racket[remote], the current branch is pushed there. Progress is written to the current output port unless @racket[quiet] is true.}
+@defproc[(git-push [remote string? "origin"] [branch (or/c string? #f) #f] [#:quiet quiet any/c #f]) void?]{Pushes a branch to a branch with the same name. With no positional arguments, the current branch is pushed to @tt{origin}; with only @racket[remote], the current branch is pushed there. A start and completion message are written to the current output port unless @racket[quiet] is true. Transfer-percentage output is temporarily disabled so that no output is performed from the libgit2 push-progress callback.}
 
-@defproc[(git-push-tag [tag string?] [remote string? "origin"] [#:quiet quiet any/c #f]) void?]{Pushes one tag. Progress is written to the current output port unless @racket[quiet] is true.}
+@defproc[(git-push-tag [tag string?] [remote string? "origin"] [#:quiet quiet any/c #f]) void?]{Pushes one tag. A start and completion message are written to the current output port unless @racket[quiet] is true. Transfer-percentage output is temporarily disabled so that no output is performed from the libgit2 push-progress callback.}
 
 Remote HTTPS operations automatically use credentials from the @tt{racket-git} credential store when an entry exists for the remote host.
 
diff --git a/tests/remote.rkt b/tests/remote.rkt
index 536b5e1..85ea495 100644
--- a/tests/remote.rkt
+++ b/tests/remote.rkt
@@ -39,8 +39,12 @@
       (collect-garbage)
       (collect-garbage)
       (collect-garbage)
-      (check-true (regexp-match? #rx"\\[git\\] push origin/master"
-                                 (get-output-string push-out)))
+      (define push-text (get-output-string push-out))
+      (check-true (regexp-match? #rx"\\[git\\] push origin/master" push-text))
+      (check-true (regexp-match? #rx"\\[git\\] push origin/master: done" push-text))
+      ;; Push progress callbacks remain installed, but must not perform output
+      ;; from FFI callback context. Percentage output would indicate a regression.
+      (check-false (regexp-match? #rx"%" push-text))
       (define quiet-out (open-output-string))
       (parameterize ([current-output-port quiet-out])
         (git 'push #:quiet #t))