diff -U 3 -H -d -r -N -- gnuplot-5.0.1.orig/docs/Makefile.am gnuplot-5.0.1.new/docs/Makefile.am
--- gnuplot-5.0.1.orig/docs/Makefile.am	2015-05-03 00:22:33.000000000 +0200
+++ gnuplot-5.0.1.new/docs/Makefile.am	2015-12-01 01:24:55.097654431 +0100
@@ -172,7 +172,7 @@
 	rm -f figures
 
 pdffigures.tex:	figures
-	@if [ -z pdffigures.tex ] ; then \
+	@if [ ! -f pdffigures.tex ] ; then \
 	  echo "\usepackage{graphicx}" > pdffigures.tex ; \
 	  echo "\usepackage{picins}" >> pdffigures.tex ; \
 	fi
diff -U 3 -H -d -r -N -- gnuplot-5.0.1.orig/docs/Makefile.in gnuplot-5.0.1.new/docs/Makefile.in
--- gnuplot-5.0.1.orig/docs/Makefile.in	2015-06-07 17:20:29.000000000 +0200
+++ gnuplot-5.0.1.new/docs/Makefile.in	2015-12-01 01:24:32.578385309 +0100
@@ -952,7 +952,7 @@
 	rm -f figures
 
 pdffigures.tex:	figures
-	@if [ -z pdffigures.tex ] ; then \
+	@if [ ! -f pdffigures.tex ] ; then \
 	  echo "\usepackage{graphicx}" > pdffigures.tex ; \
 	  echo "\usepackage{picins}" >> pdffigures.tex ; \
 	fi