diff --git a/test-suite/standalone/Makefile.am b/test-suite/standalone/Makefile.am
index ec6481029..b8a554c26 100644
--- a/test-suite/standalone/Makefile.am
+++ b/test-suite/standalone/Makefile.am
@@ -38,7 +38,8 @@ AM_LDFLAGS = $(GUILE_CFLAGS)
 
 snarfcppopts = \
   $(DEFS) $(DEFAULT_INCLUDES) $(CPPFLAGS) $(CFLAGS) -I$(top_srcdir)
-%.x: %.c
+SUFFIXES = .x
+.c.x:
 	${top_builddir}/libguile/guile-snarf -o $@ $< $(snarfcppopts)
 
 CLEANFILES = *.x