diff -ruN postgresql-7.4.7-old/src/pl/plperl/GNUmakefile postgresql-7.4.7/src/pl/plperl/GNUmakefile
--- postgresql-7.4.7-old/src/pl/plperl/GNUmakefile	2002-05-28 17:57:53.000000000 +0100
+++ postgresql-7.4.7/src/pl/plperl/GNUmakefile	2002-11-01 01:12:51.000000000 +0000
@@ -9,6 +9,9 @@
 shared_libperl = yes
 endif
 
+# Line addded for Debian - needed for any Linux build, I believe
+CFLAGS += -D_GNU_SOURCE
+
 # If we don't have a shared library and the platform doesn't allow it
 # to work without, we have to skip it.
 ifneq (,$(findstring yes, $(shared_libperl)$(allow_nonpic_in_shlib)))