diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index 11d0f1fbce43..8af369b1d17d 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -211,7 +211,7 @@ isELF() {
     exec {fd}< "$fn"
     read -r -n 4 -u "$fd" magic
     exec {fd}<&-
-    if [[ "$magic" =~ ELF ]]; then return 0; else return 1; fi
+    if [ "$magic" = $'\177ELF' ]; then return 0; else return 1; fi
 }
 
 # Return success if the specified file is a script (i.e. starts with