--- a/packages/nlp/CMakeLists.txt	2019-01-24 04:14:45.000000000 -0700
+++ b/packages/nlp/CMakeLists.txt	2019-03-22 13:00:30.351172410 -0600
@@ -2,7 +2,8 @@ cmake_minimum_required(VERSION 3.5)
 project(swipl-nlp)
 
 include("../cmake/PrologPackage.cmake")
-add_subdirectory(libstemmer_c)
+AC_CHECK_HEADERS(libstemmer.h)
+if(HAVE_LIBSTEMMER_H)
 
 AC_CHECK_FUNCS(wcsdup)
 
@@ -27,7 +28,7 @@ swipl_plugin(
 swipl_plugin(
     snowball
     C_SOURCES snowball.c
-    THREADED C_LIBS libstemmer
+    THREADED C_LIBS stemmer
     PL_LIBS snowball.pl)
 
 add_custom_target(nlp)
@@ -36,3 +37,5 @@ add_dependencies(nlp double_metaphone po
 pkg_doc(nlp
 	SECTION
 	    snowball.pl isub.pl)
+
+endif(HAVE_LIBSTEMMER_H)
--- a/packages/nlp/snowball.c	2019-01-24 04:14:45.000000000 -0700
+++ b/packages/nlp/snowball.c	2019-03-22 12:54:24.634687651 -0600
@@ -35,7 +35,7 @@
 #include <config.h>
 #include <SWI-Prolog.h>
 #include <SWI-Stream.h>
-#include "libstemmer_c/include/libstemmer.h"
+#include <libstemmer.h>
 #include <pthread.h>
 #include <string.h>
 #include <assert.h>