diff --git a/gash/compat.scm b/gash/compat.scm
index fcd2a6b..60c3545 100644
--- a/gash/compat.scm
+++ b/gash/compat.scm
@@ -56,3 +56,14 @@
     (define-public (exact-integer? x)
       (and (integer? x) (exact? x))))
   #f)
+
+(cond-expand
+  ((and guile-2 (not guile-2.2))
+   (define* (setvbuf port mode #:optional size)
+     (let ((mode (match mode
+                   ('none _IONBF)
+                   ('line _IOLBF)
+                   ('block _IOFBF))))
+       ((@ (guile) setvbuf) port mode size)))
+   (export! setvbuf))
+  (else #f))
diff --git a/tests/unit/shell.scm b/tests/unit/shell.scm
index c885a89..7dedfb4 100644
--- a/tests/unit/shell.scm
+++ b/tests/unit/shell.scm
@@ -17,6 +17,7 @@
 ;;; along with Gash.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (test-shell)
+  #:use-module (gash compat)
   #:use-module (gash compat textual-ports)
   #:use-module (gash environment)
   #:use-module (gash shell)
@@ -64,16 +65,6 @@
     (delete-recursively directory)
     result))
 
-(cond-expand
-  ((and guile-2 (not guile-2.2))
-   (define* (setvbuf port mode #:optional size)
-     (let ((mode (match mode
-                   ('none _IONBF)
-                   ('line _IOLBF)
-                   ('block _IOFBF))))
-       ((@ (guile) setvbuf) port mode size))))
-  (else #f))
-
 (define (%make-script object . forms)
   (define (write-script port)
     (chmod port #o755)