diff --git a/samples/sockets/Makefile.in b/samples/sockets/Makefile.in
index 96af3cf06c..ed5f74b03d 100644
--- a/samples/sockets/Makefile.in
+++ b/samples/sockets/Makefile.in
@@ -12,7 +12,10 @@
 top_srcdir = @top_srcdir@
 top_builddir = ../..
 program_dir = samples/wxsocket
-VPATH = :$(top_srcdir)/samples/wxsocket
+# the comment at the end of the next line is needed because otherwise autoconf
+# would remove this line completely - it contains a built-in hack to remove
+# any VPATH assignment not containing ':'
+VPATH = @PATH_IFS@$(top_srcdir)/samples/wxsocket # ':' for autoconf
 
 # Clears all default suffixes
 .SUFFIXES:	.o .cpp .c .cxx
diff --git a/src/makeprog.env.in b/src/makeprog.env.in
index e529f590f1..a875d3ee7b 100644
--- a/src/makeprog.env.in
+++ b/src/makeprog.env.in
@@ -16,7 +16,10 @@ BIN_PROGRAM = $(PROGRAM)$(PROGRAM_EXT)
 .cxx.o :
 	$(CC) -c $(CPPFLAGS) -o $@ $<
 
-VPATH = :$(top_srcdir)/$(program_dir)
+# the comment at the end of the next line is needed because otherwise autoconf
+# would remove this line completely - it contains a built-in hack to remove
+# any VPATH assignment not containing ':'
+VPATH = @PATH_IFS@$(top_srcdir)/$(program_dir) # ':' for autoconf
 
 # Set defaults from configure
 include $(top_builddir)/src/make.env