diff --git a/configure.ac b/configure.ac
index 27ffb21..5d4c10b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,5 +1,6 @@
 AC_INIT([r3], 1.0.0)
 AC_PREREQ([2.64])
+AC_USE_SYSTEM_EXTENSIONS
 AC_CONFIG_HEADERS(config.h)
 AC_CONFIG_MACRO_DIR([m4])
 AM_INIT_AUTOMAKE([foreign subdir-objects])
@@ -18,9 +19,6 @@ AC_TYPE_SIZE_T
 AC_FUNC_MALLOC
 AC_FUNC_REALLOC
 AC_CHECK_FUNCS([gettimeofday memset strchr strdup strndup strstr])
-
-
-
 PKG_PROG_PKG_CONFIG
 
 
@@ -100,14 +98,19 @@ AM_CONDITIONAL(ENABLE_JSON, test "x$enable_json" = "xyes")
 
 # This does not work because configure does not look into /opt/local/include...
 # AC_CHECK_HEADERS([check.h],[ enable_check=yes ],[ enable_check=unset ])
-AC_ARG_ENABLE(check, AS_HELP_STRING([--enable-check], [enable unit testing]))
-if test "$enable_check" = "xyes"; then
-    PKG_CHECK_MODULES(CHECK,[check >= 0.9.4],:,[
-        ifdef([AM_PATH_CHECK],
-        [AM_PATH_CHECK(,[have_check="yes"])],
-        AC_MSG_WARN([Check not found; cannot run unit tests!])
-        [have_check="no"])]
-    ])
+
+
+AC_ARG_ENABLE(check,
+              AS_HELP_STRING([--enable-check],
+                             [enable unit testing]),
+              , enable_check=unset)
+if test "x$enable_check" != "xunset" ; then
+PKG_CHECK_MODULES(CHECK,[check >= 0.9.4],:,[
+  ifdef([AM_PATH_CHECK],
+  [AM_PATH_CHECK(,[have_check="yes"])],
+  AC_MSG_WARN([Check not found; cannot run unit tests!])
+  [have_check="no"])]
+])
 fi
 AM_CONDITIONAL(HAVE_CHECK, test x"$have_check" = "xyes")
 
diff --git a/src/slug.c b/src/slug.c
index fdd039a..d19df8a 100644
--- a/src/slug.c
+++ b/src/slug.c
@@ -4,6 +4,7 @@
  *
  * Distributed under terms of the MIT license.
  */
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "config.h"
@@ -19,6 +20,8 @@ inline int contains_slug_char(const char * str) {
 
 r3_slug_t * r3_slug_new(char * path, int path_len) {
     r3_slug_t * s = zmalloc(sizeof(r3_slug_t));
+    if (!s)
+        return NULL;
     s->path = path;
     s->path_len = path_len;
 
diff --git a/tests/Makefile.am b/tests/Makefile.am
index fb15e51..8b3a270 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,13 +1,7 @@
-# INCLUDES                    = @CHECK_CFLAGS@
-# if HAVE_CHECK
-# TESTS                       = check_tree
-# else
-# TESTS                       =
-# endif
 TESTS =
 
-AM_CFLAGS=$(DEPS_CFLAGS) $(GVC_DEPS_CFLAGS) $(JSONC_CFLAGS) -I$(top_builddir) -I$(top_builddir)/include -I$(top_builddir)/src -I$(top_builddir)/3rdparty  -Wall -std=c99 -ggdb -Wall
-AM_LDFLAGS=$(DEPS_LIBS) $(GVC_DEPS_LIBS) $(JSONC_LIBS) -L$(top_builddir) -lcheck @CHECK_LIBS@ $(top_builddir)/libr3.la
+AM_CFLAGS=$(DEPS_CFLAGS) $(GVC_DEPS_CFLAGS) $(JSONC_CFLAGS) @CHECK_CFLAGS@ -I$(top_builddir) -I$(top_builddir)/include -I$(top_builddir)/src -I$(top_builddir)/3rdparty  -Wall -std=c99 -ggdb -Wall
+AM_LDFLAGS=$(DEPS_LIBS) $(GVC_DEPS_LIBS) $(JSONC_LIBS) @CHECK_LIBS@ $(top_builddir)/libr3.la
 
 if USE_JEMALLOC
 AM_CFLAGS += -ljemalloc
@@ -24,7 +18,6 @@ dist_noinst_DATA = \
 TESTS += check_slug
 check_slug_SOURCES = check_slug.c
 
-
 TESTS += check_tree
 check_tree_SOURCES = check_tree.c
 
diff --git a/tests/check_slug.c b/tests/check_slug.c
index bae4d42..aeb0544 100644
--- a/tests/check_slug.c
+++ b/tests/check_slug.c
@@ -100,11 +100,13 @@ START_TEST (test_slug_parse_with_pattern)
 {
     char * pattern = "/user/{name:\\d{3}}";
     char * errstr = NULL;
-    r3_slug_t *s = r3_slug_parse(pattern, strlen(pattern), pattern, &errstr);
+    const r3_slug_t *s = r3_slug_parse(pattern, strlen(pattern), pattern, &errstr);
+    ck_assert(s);
 
     char * out = r3_slug_to_str(s);
+    ck_assert(out);
     printf("%s\n",out);
-    zfree(out);
+    free(out);
 
     r3_slug_free(s);
 }
@@ -115,11 +117,13 @@ START_TEST (test_slug_parse_without_pattern)
 {
     char * pattern = "/user/{name}";
     char * errstr = NULL;
-    r3_slug_t *s = r3_slug_parse(pattern, strlen(pattern), pattern, &errstr);
+    const r3_slug_t *s = r3_slug_parse(pattern, strlen(pattern), pattern, &errstr);
+    ck_assert(s);
 
     char * out = r3_slug_to_str(s);
+    ck_assert(out);
     printf("%s\n",out);
-    zfree(out);
+    free(out);
 
     r3_slug_free(s);
 }