diff --git a/bin/compile b/bin/compile
index 334fc3e5cfec25b5405a5bfa7b231976d297d06a..8885c080faf5bde10c253ba6b8e5c1d5f15ff05f 100755
--- a/bin/compile
+++ b/bin/compile
@@ -104,7 +104,7 @@ LEGACY_VIRTUALENV=false
 VIRTUALENV_LOC=$MODERN_VIRTUALENV_LOC
 
 # Support "old-style" virtualenvs.
-if [ -f $CACHE_DIR/$LEGACY_VIRTUALENV_TRIGGER ]; then
+if [ -d $CACHE_DIR/$LEGACY_VIRTUALENV_TRIGGER ]; then
   LEGACY_VIRTUALENV=true
   VIRTUALENV_LOC=$LEGACY_VIRTUALENV_LOC
   CACHED_DIRS=$LEGACY_VIRTUALENV_DIRS