diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index 24deac21c59..fe801c6bb97 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -463,7 +463,9 @@ _defaultUnpack() {
     if [ -d "$fn" ]; then
 
         stripHash "$fn"
-        cp -prd --no-preserve=timestamps "$fn" $strippedName
+        # We can't preserve hardlinks because they may have been introduced by
+        # store optimization, which might break things in the build
+        cp -pr --reflink=auto --no-preserve=timestamps "$fn" $strippedName
 
     else