diff --git a/lib/Makefile.am b/lib/Makefile.am
index 75c1116..5ff09c6 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -18,7 +18,7 @@ libcomedi_la_CFLAGS = $(COMEDILIB_CFLAGS) -D_REENTRANT -DLOCALSTATEDIR=\"\$(loca
 libcomedi_la_LDFLAGS = -release $(VERSION) -Wl,--version-script=$(srcdir)/version_script
 
 calib_yacc.c + calib_yacc.h: $(srcdir)/calib_yacc.y
-	$(YACC) -d -p calib_yy -o $@ $<
+	$(YACC) -d -p calib_yy -o calib_yacc.c $<
 
 calib_lex.c: $(srcdir)/calib_lex.l
 	$(LEX) -Pcalib_yy -o$@ $<