diff -ru instantbird-1.5-src.orig/mozilla/configure.in instantbird-1.3-src/mozilla/configure.in
--- instantbird-1.5-src.orig/mozilla/configure.in	2012-11-15 13:11:47.000000000 -0800
+++ instantbird-1.5-src/mozilla/configure.in	2012-11-22 12:38:19.000000000 -0800
@@ -3911,7 +3911,7 @@
 if test -n "$MOZ_NATIVE_NSS"; then
    NSS_LIBS="$NSS_LIBS -lcrmf"
 else
-   NSS_CFLAGS='-I$(LIBXUL_DIST)/include/nss'
+   NSS_CFLAGS=`$NSS_CONFIG $nss_config_args --cflags`
 
    if test -z "$GNU_CC" -a "$OS_ARCH" = "WINNT" -o "$OS_ARCH" = "OS2"; then
        NSS_LIBS="\
diff -ru instantbird-1.5-src.orig/purple/libpurple/Makefile.in instantbird-1.3-src/purple/libpurple/Makefile.in
--- instantbird-1.5-src.orig/purple/libpurple/Makefile.in	2012-11-15 13:03:51.000000000 -0800
+++ instantbird-1.5-src/purple/libpurple/Makefile.in	2012-11-22 12:42:54.000000000 -0800
@@ -19,7 +19,7 @@
 VISIBILITY_FLAGS=
 
 ifeq (,$(filter WINNT Darwin,$(OS_ARCH)))
-LOCAL_INCLUDES	= $(GLIB_CFLAGS) $(LIBXML2_CFLAGS)
+LOCAL_INCLUDES	= $(NSS_CFLAGS) $(GLIB_CFLAGS) $(LIBXML2_CFLAGS)
 else
 LOCAL_INCLUDES  = -I$(DIST)/include/glib
 SHARED_LIBRARY_LIBS += $(foreach lib,glib xml2,../libraries/$(lib)/$(LIB_PREFIX)$(lib).$(LIB_SUFFIX))