diff --git a/examples/initfail.c b/examples/initfail.c
index 546b001..7f223c3 100644
--- a/examples/initfail.c
+++ b/examples/initfail.c
@@ -2,7 +2,7 @@
 int
 main(int argc, char **argv)
 {
-	argc = argc;
-	argv = argv;
+	(void) argc;
+	(void) argv;
 	return 1;
 }
diff --git a/libscu-c/Makefile.scu b/libscu-c/Makefile.scu
index e5e095f..886721c 100644
--- a/libscu-c/Makefile.scu
+++ b/libscu-c/Makefile.scu
@@ -16,8 +16,17 @@ build: $(TESTCASES)
 clean::
 	rm -f $(TESTCASES) $(patsubst %,%.o,$(TESTCASES)) $(patsubst %,valgrind.%.log,$(TESTCASES))
 
+
+LDFLAGS:=-L$(SCU_DIR)/libscu-c/ -lscu-c -lpthread
+
+ifeq ($(shell uname), Darwin)
+	# libargp may be installed with homebrew
+	#    brew install argp-standalone
+	LDFLAGS+=-largp
+endif
+
 $(TESTCASES): %:%.o $(SCU_DIR)/libscu-c/libscu-c.a
-	$(CC) -o $@ $< -L$(SCU_DIR)/libscu-c/ -lscu-c
+	$(CC) -o $@ $< $(LDFLAGS)
 
 $(SCU_DIR)/libscu-c/libscu-c.a:
 	make -C $(SCU_DIR)/libscu-c
diff --git a/libscu-c/src/scu.c b/libscu-c/src/scu.c
index b0d60d3..4ba90e8 100644
--- a/libscu-c/src/scu.c
+++ b/libscu-c/src/scu.c
@@ -1,10 +1,10 @@
 #include <argp.h>
 #include <assert.h>
+#include <pthread.h>
 #include <setjmp.h>
 #include <signal.h>
 #include <stdlib.h>
 #include <sys/ioctl.h>
-#include <sys/syscall.h>
 #include <time.h>
 #include <unistd.h>
 
@@ -296,13 +296,13 @@ _scu_get_time_diff(struct timespec startt, struct timespec endt)
 }
 
 static bool _scu_fatal_assert_jmpbuf_valid;
-static pid_t _scu_fatal_assert_allowed_thread_id;
+static pthread_t _scu_fatal_assert_allowed_thread_id;
 static jmp_buf _scu_fatal_assert_jmpbuf;
 
-static pid_t
+static pthread_t
 _scu_get_current_thread_id(void)
 {
-	return syscall(SYS_gettid);
+	return pthread_self();
 }
 
 void