diff --git a/Makefile.config.in b/Makefile.config.in
index 9c655067..2492f63b 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -5,8 +5,15 @@
 
 SHELL = @SHELL@
 
-top_srcdir = $(path_to_top)/@top_srcdir@
-srcdir = $(top_srcdir)/$(shell pwd | sed 's!.*/\($(shell echo $(path_to_top) | sed 's!\.\.![^/]*!')\)$$!\1!')
+CURPATH = $(shell pwd)
+TOPPATH = $(shell cd $(path_to_top) && pwd)
+RELPATH = $(shell echo '$(CURPATH)' | sed 's,$(TOPPATH),,;s,^/,,;s,\([a-z0-9]\)$$,\1/,')
+
+PATHSCRIPT = case '@top_srcdir@' in /*) ;; *) echo $(path_to_top)/;; esac
+PATHPREFIX = $(shell $(PATHSCRIPT))
+
+top_srcdir = $(PATHPREFIX)@top_srcdir@
+srcdir = $(top_srcdir)/$(RELPATH)
 top_builddir = $(path_to_top)
 prefix = @prefix@
 exec_prefix = @exec_prefix@
@@ -56,7 +63,7 @@ LIBDIR = @LIBDIR@
 LOCALEDIR = @LOCALEDIR@
 LUA_CFLAGS = @LUA_CFLAGS@
 LUA_LIBS = @LUA_LIBS@
-MKINSTALLDIRS = $(top_srcdir)/@MKINSTALLDIRS@
+MKINSTALLDIRS = $(PATHPREFIX)@MKINSTALLDIRS@
 MSGFMT = @MSGFMT@
 OPENSSL_CFLAGS = @OPENSSL_CFLAGS@
 PACKAGE = @PACKAGE@
diff --git a/Makefile.lib b/Makefile.lib
index 609a36cf..a0fda102 100644
--- a/Makefile.lib
+++ b/Makefile.lib
@@ -14,10 +14,6 @@ else
 	mquiet = quiet_
 endif
 
-CURPATH = $(shell pwd)
-TOPPATH = $(shell cd $(path_to_top) && pwd)
-RELPATH = $(shell echo '$(CURPATH)' | sed 's,$(TOPPATH),,;s,^/,,;s,\([a-z0-9]\)$$,\1/,')
-
 # Show the command (quiet or non-quiet version based on the assignment
 # just above) and then execute it.
 ncmd = $(if $($(quiet)cmd_$(1)),echo $($(quiet)cmd_$(1)) &&) $(cmd_$(1))