diff --git a/Makefile.global.in b/Makefile.global.in
index 03c21416f..7cdbcd5d9 100644
--- a/Makefile.global.in
+++ b/Makefile.global.in
@@ -11,6 +11,9 @@
 
 citus_abs_srcdir:=@abs_top_srcdir@/${citus_subdir}
 citus_abs_top_srcdir:=@abs_top_srcdir@
+postgres_abs_srcdir:=@POSTGRES_SRCDIR@
+postgres_abs_builddir:=@POSTGRES_BUILDDIR@
+
 PG_CONFIG:=@PG_CONFIG@
 PGXS:=$(shell $(PG_CONFIG) --pgxs)
 
diff --git a/configure b/configure
index e122b8702..3325bb70e 100755
--- a/configure
+++ b/configure
@@ -586,6 +586,8 @@ PACKAGE_URL=''
 
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
+POSTGRES_BUILDDIR
+POSTGRES_SRCDIR
 CITUS_CFLAGS
 OBJEXT
 EXEEXT
@@ -2540,6 +2542,14 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 CFLAGS="$SAVE_CFLAGS"
 
+
+# Locate source and build directory of the postgres we're building
+# against. Can't rely on either still being present, but e.g. optional
+# test infrastructure can rely on it.
+POSTGRES_SRCDIR=$(grep ^abs_top_srcdir $(dirname $($PG_CONFIG --pgxs))/../Makefile.global|cut -d ' ' -f3-)
+POSTGRES_BUILDDIR=$(grep ^abs_top_builddir $(dirname $($PG_CONFIG --pgxs))/../Makefile.global|cut -d ' ' -f3-)
+
+
 # check for a number of CFLAGS that make development easier
 
 # CITUSAC_PROG_CC_CFLAGS_OPT
@@ -2938,6 +2948,10 @@ fi
 
 CITUS_CFLAGS="$CITUS_CFLAGS"
 
+POSTGRES_SRCDIR="$POSTGRES_SRCDIR"
+
+POSTGRES_BUILDDIR="$POSTGRES_BUILDDIR"
+
 
 ac_config_files="$ac_config_files Makefile.global"
 
diff --git a/configure.in b/configure.in
index e0903260d..faf6721d1 100644
--- a/configure.in
+++ b/configure.in
@@ -63,6 +63,14 @@ SAVE_CFLAGS="$CFLAGS"
 AC_PROG_CC([$($PG_CONFIG --cc)])
 CFLAGS="$SAVE_CFLAGS"
 
+
+# Locate source and build directory of the postgres we're building
+# against. Can't rely on either still being present, but e.g. optional
+# test infrastructure can rely on it.
+POSTGRES_SRCDIR=$(grep ^abs_top_srcdir $(dirname $($PG_CONFIG --pgxs))/../Makefile.global|cut -d ' ' -f3-)
+POSTGRES_BUILDDIR=$(grep ^abs_top_builddir $(dirname $($PG_CONFIG --pgxs))/../Makefile.global|cut -d ' ' -f3-)
+
+
 # check for a number of CFLAGS that make development easier
 
 # CITUSAC_PROG_CC_CFLAGS_OPT
@@ -102,6 +110,8 @@ CITUSAC_PROG_CC_CFLAGS_OPT([-Wmissing-declarations])
 CITUSAC_PROG_CC_CFLAGS_OPT([-Wmissing-prototypes])
 
 AC_SUBST(CITUS_CFLAGS, "$CITUS_CFLAGS")
+AC_SUBST(POSTGRES_SRCDIR, "$POSTGRES_SRCDIR")
+AC_SUBST(POSTGRES_BUILDDIR, "$POSTGRES_BUILDDIR")
 
 AC_CONFIG_FILES([Makefile.global])
 AC_CONFIG_HEADERS([src/include/citus_config.h])