--- whois-5.2.18/Makefile.orig	2017-08-22 18:48:50.000000000 +0200
+++ whois-5.2.18/Makefile	2017-09-15 10:02:37.915199229 +0200
@@ -32,12 +32,12 @@
 DEFS += -DLOCALEDIR=\"$(BASEDIR)$(prefix)/share/locale\"
 endif
 
-ifeq ($(shell pkg-config --exists 'libidn2 >= 2.0.3' || echo NO),)
-whois_LDADD += $(shell pkg-config --libs libidn2)
-DEFS += -DHAVE_LIBIDN2 $(shell pkg-config --cflags libidn2)
-else ifeq ($(shell pkg-config --exists 'libidn' || echo NO),)
-whois_LDADD += $(shell pkg-config --libs libidn)
-DEFS += -DHAVE_LIBIDN $(shell pkg-config --cflags libidn)
+ifeq ($(shell ${PKG_CONFIG} --exists 'libidn2 >= 2.0.3' || echo NO),)
+whois_LDADD += $(shell ${PKG_CONFIG} --libs libidn2)
+DEFS += -DHAVE_LIBIDN2 $(shell ${PKG_CONFIG} --cflags libidn2)
+else ifeq ($(shell ${PKG_CONFIG} --exists 'libidn' || echo NO),)
+whois_LDADD += $(shell ${PKG_CONFIG} --libs libidn)
+DEFS += -DHAVE_LIBIDN $(shell ${PKG_CONFIG} --cflags libidn)
 endif
 
 ifdef HAVE_ICONV