diff --git a/tests/headers/posix/strings_h.c b/tests/headers/posix/strings_h.c
index 0a2fa84..2051c8b 100644
--- a/tests/headers/posix/strings_h.c
+++ b/tests/headers/posix/strings_h.c
@@ -32,6 +32,10 @@
 
 static void strings_h() {
   FUNCTION(ffs, int (*f)(int));
+#if !defined(__GLIBC__)
+  FUNCTION(ffsl, int (*f)(long));
+  FUNCTION(ffsll, int (*f)(long long));
+#endif
   FUNCTION(strcasecmp, int (*f)(const char*, const char*));
   FUNCTION(strcasecmp_l, int (*f)(const char*, const char*, locale_t));
   FUNCTION(strncasecmp, int (*f)(const char*, const char*, size_t));
diff --git a/tests/strings_test.cpp b/tests/strings_test.cpp
index ac327d4..0226d1a 100644
--- a/tests/strings_test.cpp
+++ b/tests/strings_test.cpp
@@ -38,6 +38,48 @@
   ASSERT_EQ(32, ffs(0x80000000));
 }
 
+TEST(STRINGS_TEST, ffsl) {
+  ASSERT_EQ( 0, ffsl(0x00000000L));
+  ASSERT_EQ( 1, ffsl(0x00000001L));
+  ASSERT_EQ( 6, ffsl(0x00000020L));
+  ASSERT_EQ(11, ffsl(0x00000400L));
+  ASSERT_EQ(16, ffsl(0x00008000L));
+  ASSERT_EQ(17, ffsl(0x00010000L));
+  ASSERT_EQ(22, ffsl(0x00200000L));
+  ASSERT_EQ(27, ffsl(0x04000000L));
+  ASSERT_EQ(32, ffsl(0x80000000L));
+#if defined(__LP64__)
+  ASSERT_EQ(33, ffsl(0x0000000100000000L));
+  ASSERT_EQ(38, ffsl(0x0000002000000000L));
+  ASSERT_EQ(43, ffsl(0x0000040000000000L));
+  ASSERT_EQ(48, ffsl(0x0000800000000000L));
+  ASSERT_EQ(49, ffsl(0x0001000000000000L));
+  ASSERT_EQ(54, ffsl(0x0020000000000000L));
+  ASSERT_EQ(59, ffsl(0x0400000000000000L));
+  ASSERT_EQ(64, ffsl(0x8000000000000000L));
+#endif
+}
+
+TEST(STRINGS_TEST, ffsll) {
+  ASSERT_EQ( 0, ffsll(0x0000000000000000LL));
+  ASSERT_EQ( 1, ffsll(0x0000000000000001LL));
+  ASSERT_EQ( 6, ffsll(0x0000000000000020LL));
+  ASSERT_EQ(11, ffsll(0x0000000000000400LL));
+  ASSERT_EQ(16, ffsll(0x0000000000008000LL));
+  ASSERT_EQ(17, ffsll(0x0000000000010000LL));
+  ASSERT_EQ(22, ffsll(0x0000000000200000LL));
+  ASSERT_EQ(27, ffsll(0x0000000004000000LL));
+  ASSERT_EQ(32, ffsll(0x0000000080000000LL));
+  ASSERT_EQ(33, ffsll(0x0000000100000000LL));
+  ASSERT_EQ(38, ffsll(0x0000002000000000LL));
+  ASSERT_EQ(43, ffsll(0x0000040000000000LL));
+  ASSERT_EQ(48, ffsll(0x0000800000000000LL));
+  ASSERT_EQ(49, ffsll(0x0001000000000000LL));
+  ASSERT_EQ(54, ffsll(0x0020000000000000LL));
+  ASSERT_EQ(59, ffsll(0x0400000000000000LL));
+  ASSERT_EQ(64, ffsll(0x8000000000000000LL));
+}
+
 TEST(STRINGS_TEST, strcasecmp) {
   ASSERT_EQ(0, strcasecmp("hello", "HELLO"));
   ASSERT_LT(strcasecmp("hello1", "hello2"), 0);