diff --git a/collects/setup/parallel-build.rkt b/collects/setup/parallel-build.rkt
index dd311faf7f..5fd1969710 100644
--- a/collects/setup/parallel-build.rkt
+++ b/collects/setup/parallel-build.rkt
@@ -3,6 +3,7 @@
 (require racket/future
          racket/list
          racket/match
+         racket/path
          setup/collects
          unstable/generics)
 
@@ -21,6 +22,12 @@
 
   (define executable (parameterize ([current-directory (find-system-path 'orig-dir)])
                        (find-executable-path (find-system-path 'exec-file) #f)))
+  (define collects-dir (let ([p (find-system-path 'collects-dir)])
+                         (if (complete-path? p)
+                             p
+                             (path->complete-path p (or (path-only executable)
+                                                        (find-system-path 'orig-dir))))))
+                        
   (define (send/msg x ch)
     (write x ch)
     (flush-output ch))
@@ -28,7 +35,7 @@
     (let-values ([(s o in e) (subprocess #f #f (current-error-port) 
                                          executable
                                          "-X"
-                                         (path->string (find-system-path 'collects-dir))
+                                         (path->string collects-dir)
                                          "-l"
                                          process-worker-library)])
       (send/msg i in)
diff --git a/src/racket/src/file.c b/src/racket/src/file.c
index ede9f768f6..3a893b57b4 100644
--- a/src/racket/src/file.c
+++ b/src/racket/src/file.c
@@ -3570,10 +3570,16 @@ static char *do_path_to_complete_path(char *filename, long ilen, const char *wrt
 
     if (!wrt) {
       Scheme_Object *wd;
-      wd = CURRENT_WD();
-      wrt = SCHEME_PATH_VAL(wd);
-      wlen = SCHEME_PATH_LEN(wd);
-      scheme_security_check_file("path->complete-path", NULL, SCHEME_GUARD_FILE_EXISTS);
+      if (scheme_current_thread) {
+        wd = CURRENT_WD();
+        wrt = SCHEME_PATH_VAL(wd);
+        wlen = SCHEME_PATH_LEN(wd);
+        scheme_security_check_file("path->complete-path", NULL, SCHEME_GUARD_FILE_EXISTS);
+      } else {
+        int actlen;
+        wrt = scheme_os_getcwd(NULL, 0, &actlen, 1);
+        wlen = actlen - 1;
+      }
     }
 
     if (kind == SCHEME_WINDOWS_PATH_KIND) {
@@ -3614,7 +3620,7 @@ static char *do_path_to_complete_path(char *filename, long ilen, const char *wrt
     }
     memcpy(naya + wlen, filename, ilen);
     naya[wlen + ilen] = 0;
-    
+
     return naya;
   }