Index: tests.scm
==================================================================
--- tests.scm
+++ tests.scm
@@ -1777,11 +1777,11 @@
 		))))))
 
 ;; (tests:run-dot (list "digraph tests {" "a -> b" "}") "plain")
 
 (define (tests:run-dot indat outtype) ;; outtype is plain, fig, dot, etc. http://www.graphviz.org/content/output-formats
-  (let-values (((inp oup pid)(process "env -i PATH=$PATH dot" (list "-T" outtype))))
+  (let-values (((inp oup pid)(process "env -i PATH=\"$PATH\" dot" (list "-T" outtype))))
     (with-output-to-port oup
       (lambda ()
 	(map print indat)))
     (close-output-port oup)
     (let ((res (with-input-from-port inp
@@ -1799,14 +1799,14 @@
     (tests:write-dot-file testrecords dfile sizex sizey)
     (if (common:file-exists? fname)
 	(let ((res (with-input-from-file fname
 		     (lambda ()
 		       (read-lines)))))
-	  (system (conc "env -i PATH=$PATH dot -T " outtype " < " dfile " > " fname "&"))
+	  (system (conc "env -i PATH=\"$PATH\" dot -T " outtype " < " dfile " > " fname "&"))
 	  res)
 	(begin
-	  (system (conc "env -i PATH=$PATH dot -T " outtype " < " dfile " > " fname))
+	  (system (conc "env -i PATH=\"$PATH\" dot -T " outtype " < " dfile " > " fname))
 	  (with-input-from-file fname
 	    (lambda ()
 	      (read-lines)))))))