diff --git a/CHR/Makefile.in b/CHR/Makefile.in
index 0993574f1..fb0527af9 100644
--- a/CHR/Makefile.in
+++ b/CHR/Makefile.in
@@ -85,9 +85,9 @@ CHR_EXAMPLES= $(srcdir)/chr/examples/allentable.pl \
 
 
 install: $(CHR_TOP) $(CHR_LICENSE) $(CHR_PROGRAMS) $(CHR_EXAMPLES)
-	-mkdir $(DESTDIR)$(LIBDIR)/library
-	-mkdir $(DESTDIR)$(LIBDIR)/library/chr
-	-mkdir $(DESTDIR)$(LIBDIR)/library/chr/examples
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/chr
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/chr/examples
 	for h in $(CHR_TOP); do $(INSTALL_DATA) $$h $(DESTDIR)$(LIBDIR)/library; done
 	for h in $(CHR_LICENSE); do $(INSTALL_DATA) $$h $(DESTDIR)$(LIBDIR)/library; done
 	for h in $(CHR_PROGRAMS); do $(INSTALL_DATA) $$h $(DESTDIR)$(LIBDIR)/library/chr; done
diff --git a/CLPQR/Makefile.in b/CLPQR/Makefile.in
index b7bc96c74..f7225aa13 100644
--- a/CLPQR/Makefile.in
+++ b/CLPQR/Makefile.in
@@ -129,13 +129,13 @@ CLPQR_EXAMPLES_SESSION= $(srcdir)/clpqr/examples/SESSION/010 \
 
 install: $(CLPR_TOP) $(CLPQ_TOP) $(CLPQR_LICENSE) $(CLPQR_PROGRAMS) $(CLPQR_LOCAL)\
 	$(CLPQR_EXAMPLES) $(CLPQR_EXAMPLES_MONASH) $(CLPQR_EXAMPLES_SESSION)
-	-mkdir $(DESTDIR)$(LIBDIR)/library
-	-mkdir $(DESTDIR)$(LIBDIR)/library/clpq
-	-mkdir $(DESTDIR)$(LIBDIR)/library/clpqr
-	-mkdir $(DESTDIR)$(LIBDIR)/library/clpr
-	-mkdir $(DESTDIR)$(LIBDIR)/library/clpqr/examples
-	-mkdir $(DESTDIR)$(LIBDIR)/library/clpqr/examples/SESSION
-	-mkdir $(DESTDIR)$(LIBDIR)/library/clpqr/examples/monash
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/clpq
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/clpqr
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/clpr
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/clpqr/examples
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/clpqr/examples/SESSION
+	-mkdir -p $(DESTDIR)$(LIBDIR)/library/clpqr/examples/monash
 	for h in $(CLPQ_TOP); do $(INSTALL_DATA) $$h $(DESTDIR)$(LIBDIR)/library; done
 	for h in $(CLPR_TOP); do $(INSTALL_DATA) $$h $(DESTDIR)$(LIBDIR)/library; done
 	for h in $(CLPQR_LICENSE); do $(INSTALL_DATA) $$h $(DESTDIR)$(LIBDIR)/library; done