diff --git a/test/run b/test/run
index 63dca3b42a..9ef2746d38 100755
--- a/test/run
+++ b/test/run
@@ -26,10 +26,9 @@ failed=0
 
 PATH=/bin:/usr/bin:$HOME/bin:`pwd`
 
-# don't use $$ in file names to avoid spurious diffs
-RUNFILE=/tmp/gorun-$USER
-TMP1FILE=/tmp/gotest1-$USER
-TMP2FILE=/tmp/gotest2-$USER
+RUNFILE=/tmp/gorun-$$-$USER
+TMP1FILE=/tmp/gotest1-$$-$USER
+TMP2FILE=/tmp/gotest2-$$-$USER
 
 # don't run the machine out of memory: limit individual processes to 4GB.
 # on thresher, 3GB suffices to run the tests; with 2GB, peano fails.