diff --git a/src/cmp/cmpos-run.lsp b/src/cmp/cmpos-run.lsp
index 418751c3d..4008b3a6a 100755
--- a/src/cmp/cmpos-run.lsp
+++ b/src/cmp/cmpos-run.lsp
@@ -51,18 +51,25 @@
          (program (car program)))
     (with-current-directory
      ;; when compiling ECL itself, we only have low-level functions
-     ;; available, otherwise we can use run-program and get proper
-     ;; quoting of arguments
-     #+ecl-min (multiple-value-bind (output-stream return-status pid)
-                   (si:run-program-inner program args :default nil)
-                 (setf output (collect-lines output-stream))
-                 (multiple-value-setq (return-status result)
-                   (si:waitpid pid t)))
-     #-ecl-min (multiple-value-bind (output-stream return-status process-obj)
-                   (ext:run-program program args :wait nil)
-                 (setf output (collect-lines output-stream))
-                 (multiple-value-setq (return-status result)
-                   (ext:external-process-wait process-obj t)))))
+     ;; available ...
+     #+(and ecl-min (not cygwin))
+     (multiple-value-bind (output-stream return-status pid)
+         (si:run-program-inner program args :default nil)
+       (setf output (collect-lines output-stream))
+       (multiple-value-setq (return-status result)
+         (si:waitpid pid t)))
+     ;; ... otherwise we can use run-program and get proper
+     ;; quoting of arguments ...
+     #+(and (not ecl-min) (not cygwin))
+     (multiple-value-bind (output-stream return-status process-obj)
+         (ext:run-program program args :wait nil)
+       (setf output (collect-lines output-stream))
+       (multiple-value-setq (return-status result)
+         (ext:external-process-wait process-obj t)))
+     ;; ... unless we're running on cygwin which has problems with
+     ;; forking so we have to use si:system
+     #+cygwin
+     (setf result (si:system (format nil "~A~{ ~A~}" program args)))))
   (cond ((null result)
          (cerror "Continues anyway."
                  "Unable to execute:~%(EXT:RUN-PROGRAM ~S ~S)"