diff --git a/pkgs/stdenv/cygwin/rebase-i686.sh b/pkgs/stdenv/cygwin/rebase-i686.sh
index e97dc66c0ad..091c9044d93 100644
--- a/pkgs/stdenv/cygwin/rebase-i686.sh
+++ b/pkgs/stdenv/cygwin/rebase-i686.sh
@@ -1,10 +1,10 @@
-postFixupHooks+=(_cygwinFixAutoImageBase)
+fixupOutputHooks+=(_cygwinFixAutoImageBase)
 
 _cygwinFixAutoImageBase() {
-    if [ "$dontRebase" == 1 ]; then
+    if [ "$dontRebase" == 1 ] || [ ! -d "$prefix" ]; then
         return
     fi
-    find $out -name "*.dll" | while read DLL; do
+    find "$prefix" -name "*.dll" -type f | while read DLL; do
         if [ -f /etc/rebasenix.nextbase ]; then
             NEXTBASE="$(</etc/rebasenix.nextbase)"
         fi
diff --git a/pkgs/stdenv/cygwin/rebase-x86_64.sh b/pkgs/stdenv/cygwin/rebase-x86_64.sh
index a79c6257460..77adc52d53b 100644
--- a/pkgs/stdenv/cygwin/rebase-x86_64.sh
+++ b/pkgs/stdenv/cygwin/rebase-x86_64.sh
@@ -1,10 +1,10 @@
-postFixupHooks+=(_cygwinFixAutoImageBase)
+fixupOutputHooks+=(_cygwinFixAutoImageBase)
 
 _cygwinFixAutoImageBase() {
-    if [ "$dontRebase" == 1 ]; then
+    if [ "$dontRebase" == 1 ] || [ ! -d "$prefix" ]; then
         return
     fi
-    find $out -name "*.dll" | while read DLL; do
+    find "$prefix" -name "*.dll" -type f | while read DLL; do
         if [ -f /etc/rebasenix.nextbase ]; then
             NEXTBASE="$(</etc/rebasenix.nextbase)"
         fi