diff --git a/string/Makefile b/string/Makefile
index 1ec547e9fb..e133b53266 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -62,7 +62,8 @@ CFLAGS-test-ffs.c = -fno-builtin
 
 ifeq ($(cross-compiling),no)
 tests: $(objpfx)tst-svc.out
-$(objpfx)tst-svc.out: $(objpfx)tst-svc
-	$(built-program-cmd) $< > $@
+$(objpfx)tst-svc.out: tst-svc.input $(objpfx)tst-svc
+	GCONV_PATH=$(common-objpfx)iconvdata LC_ALL=C \
+	  $(built-program-cmd) < $(word 1,$^) > $@
 	-cmp tst-svc.expect $(objpfx)tst-svc.out
 endif