diff --git a/src/libstrongswan/Makefile.am b/src/libstrongswan/Makefile.am
index 827e0adb2..db8e9c23a 100644
--- a/src/libstrongswan/Makefile.am
+++ b/src/libstrongswan/Makefile.am
@@ -236,8 +236,8 @@ $(srcdir)/crypto/proposal/proposal_keywords_static.h: $(srcdir)/crypto/proposal/
 $(srcdir)/crypto/proposal/proposal_keywords_static.c:	$(srcdir)/crypto/proposal/proposal_keywords_static.txt \
 														$(srcdir)/crypto/proposal/proposal_keywords_static.h
 		$(AM_V_GEN) \
-		$(GPERF) -N proposal_get_token_static -m 10 -C -G -c -t -D < \
-												$(srcdir)/crypto/proposal/proposal_keywords_static.txt > $@
+		$(GPERF) -N proposal_get_token_static -m 10 -C -G -c -t -D \
+			--output-file=$@ $<
 
 if STATIC_PLUGIN_CONSTRUCTORS
 BUILT_SOURCES += $(srcdir)/plugin_constructors.c
diff --git a/src/starter/Makefile.am b/src/starter/Makefile.am
index 759d179d3..1dc656fed 100644
--- a/src/starter/Makefile.am
+++ b/src/starter/Makefile.am
@@ -54,7 +54,8 @@ keywords.h: $(srcdir)/keywords.h.in
 
 keywords.c:	$(srcdir)/keywords.txt keywords.h
 		$(AM_V_GEN) \
-		$(GPERF) -m 10 -C -G -D -t < $(srcdir)/keywords.txt > $@
+		$(GPERF) -m 10 -C -G -D -t \
+			--output-file=$@ $<
 
 install-exec-local :
 		test -e "$(DESTDIR)${sysconfdir}/ipsec.d" || $(INSTALL) -d "$(DESTDIR)$(sysconfdir)/ipsec.d" || true
diff --git a/src/stroke/Makefile.am b/src/stroke/Makefile.am
index 5c04b5ae7..3b7c465b6 100644
--- a/src/stroke/Makefile.am
+++ b/src/stroke/Makefile.am
@@ -19,4 +19,5 @@ stroke_keywords.h: $(srcdir)/stroke_keywords.h.in
 
 stroke_keywords.c:	$(srcdir)/stroke_keywords.txt stroke_keywords.h
 		$(AM_V_GEN) \
-		$(GPERF) -m 10 -D -C -G -t < $(srcdir)/stroke_keywords.txt > $@
+		$(GPERF) -m 10 -D -C -G -t \
+			--output-file=$@ $<