diff --git a/pkgs/applications/networking/browsers/firefox/8.0.nix b/pkgs/applications/networking/browsers/firefox/8.0.nix
index e56d2f1e1e6..823d6e0cbd2 100644
--- a/pkgs/applications/networking/browsers/firefox/8.0.nix
+++ b/pkgs/applications/networking/browsers/firefox/8.0.nix
@@ -161,7 +161,7 @@ rec {
             file $i;
             if file $i | grep executable &>/dev/null; then 
 	        rm "$out/bin/$(basename "$i")"
-                echo -e '#! /bin/sh\n"'"$i"'" "$@"' > "$out/bin/$(basename "$i")"
+                echo -e '#! /bin/sh\nexec "'"$i"'" "$@"' > "$out/bin/$(basename "$i")"
                 chmod a+x "$out/bin/$(basename "$i")"
             fi;
         done;
diff --git a/pkgs/applications/networking/browsers/firefox/9.0.nix b/pkgs/applications/networking/browsers/firefox/9.0.nix
index a0d32691451..f14eb05899d 100644
--- a/pkgs/applications/networking/browsers/firefox/9.0.nix
+++ b/pkgs/applications/networking/browsers/firefox/9.0.nix
@@ -161,7 +161,7 @@ rec {
             file $i;
             if file $i | grep executable &>/dev/null; then 
 	        rm "$out/bin/$(basename "$i")"
-                echo -e '#! /bin/sh\n"'"$i"'" "$@"' > "$out/bin/$(basename "$i")"
+                echo -e '#! /bin/sh\nexec "'"$i"'" "$@"' > "$out/bin/$(basename "$i")"
                 chmod a+x "$out/bin/$(basename "$i")"
             fi;
         done;