diff --git a/libc/include/string.h b/libc/include/string.h
index 2b7d47c..7801ee9 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -175,7 +175,6 @@
     return __strlcpy_chk(dest, src, size, bos);
 }
 
-#if !defined(__clang__)
 extern size_t __strlcat_real(char* __restrict, const char* __restrict, size_t)
     __asm__(__USER_LABEL_PREFIX__ "strlcat");
 __errordecl(__strlcat_error, "strlcat called with size bigger than buffer");
@@ -186,6 +185,7 @@
 size_t strlcat(char* __restrict dest, const char* __restrict src, size_t size) {
     size_t bos = __bos(dest);
 
+#if !defined(__clang__)
     // Compiler doesn't know destination size. Don't call __strlcat_chk
     if (bos == __BIONIC_FORTIFY_UNKNOWN_SIZE) {
         return __strlcat_real(dest, src, size);
@@ -202,10 +202,10 @@
     if (__builtin_constant_p(size) && (size > bos)) {
         __strlcat_error();
     }
+#endif /* !defined(__clang__) */
 
     return __strlcat_chk(dest, src, size, bos);
 }
-#endif /* !defined(__clang__) */
 
 __BIONIC_FORTIFY_INLINE
 size_t strlen(const char *s) {
diff --git a/libc/include/strings.h b/libc/include/strings.h
index faa12a4..e72798b 100644
--- a/libc/include/strings.h
+++ b/libc/include/strings.h
@@ -50,12 +50,12 @@
 int	 strcasecmp(const char *, const char *);
 int	 strncasecmp(const char *, const char *, size_t);
 
-#if defined(__BIONIC_FORTIFY) && !defined(__clang__)
+#if defined(__BIONIC_FORTIFY)
 __BIONIC_FORTIFY_INLINE
 void bzero (void *s, size_t n) {
     __builtin___memset_chk(s, '\0', n, __builtin_object_size (s, 0));
 }
-#endif /* defined(__BIONIC_FORTIFY) && !defined(__clang__) */
+#endif /* defined(__BIONIC_FORTIFY) */
 
 __END_DECLS
 
diff --git a/libc/include/sys/stat.h b/libc/include/sys/stat.h
index c9ad23d..c7715a3 100644
--- a/libc/include/sys/stat.h
+++ b/libc/include/sys/stat.h
@@ -129,7 +129,7 @@
 extern int    mknod(const char *, mode_t, dev_t);
 extern mode_t umask(mode_t);
 
-#if defined(__BIONIC_FORTIFY) && !defined(__clang__)
+#if defined(__BIONIC_FORTIFY)
 
 extern mode_t __umask_chk(mode_t);
 extern mode_t __umask_real(mode_t)
@@ -138,15 +138,17 @@
 
 __BIONIC_FORTIFY_INLINE
 mode_t umask(mode_t mode) {
+#if !defined(__clang__)
   if (__builtin_constant_p(mode)) {
     if ((mode & 0777) != mode) {
       __umask_invalid_mode();
     }
     return __umask_real(mode);
   }
+#endif
   return __umask_chk(mode);
 }
-#endif /* defined(__BIONIC_FORTIFY) && !defined(__clang__) */
+#endif /* defined(__BIONIC_FORTIFY) */
 
 
 #define  stat64    stat
diff --git a/tests/fortify_test.cpp b/tests/fortify_test.cpp
index 68b5517..d8f0e76 100644
--- a/tests/fortify_test.cpp
+++ b/tests/fortify_test.cpp
@@ -17,6 +17,8 @@
 #include <gtest/gtest.h>
 #include <string.h>
 #include <stdarg.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 // We have to say "DeathTest" here so gtest knows to run this test (which exits)
 // in its own process. Unfortunately, the C preprocessor doesn't give us an
@@ -204,6 +206,20 @@
 }
 #endif
 
+#ifndef __clang__
+// This test is disabled in clang because clang doesn't properly detect
+// this buffer overflow. TODO: Fix clang.
+TEST(DEATHTEST, strlcat_fortified2) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  foo myfoo;
+  strcpy(myfoo.a, "01");
+  myfoo.one[0] = '\0';
+  size_t n = strlen(myfoo.a);
+  ASSERT_EXIT(strlcat(myfoo.one, myfoo.a, n),
+              testing::KilledBySignal(SIGABRT), "");
+}
+#endif
+
 #endif /* __BIONIC__ */
 
 #ifndef __clang__
@@ -268,6 +284,14 @@
   ASSERT_EXIT(snprintf(myfoo.b, n, "a%s", myfoo.a), testing::KilledBySignal(SIGABRT), "");
 }
 
+TEST(DEATHTEST, bzero_fortified2) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  foo myfoo;
+  memcpy(myfoo.b, "0123456789", sizeof(myfoo.b));
+  size_t n = atoi("11");
+  ASSERT_EXIT(bzero(myfoo.b, n), testing::KilledBySignal(SIGABRT), "");
+}
+
 #endif /* defined(_FORTIFY_SOURCE) && _FORTIFY_SOURCE=2 */
 
 #if __BIONIC__
@@ -337,6 +361,16 @@
   ASSERT_EXIT(strlcpy(bufb, bufa, n), testing::KilledBySignal(SIGABRT), "");
 }
 
+TEST(DEATHTEST, strlcat_fortified) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  char bufa[15];
+  char bufb[10];
+  bufb[0] = '\0';
+  strcpy(bufa, "01234567890123");
+  size_t n = strlen(bufa);
+  ASSERT_EXIT(strlcat(bufb, bufa, n), testing::KilledBySignal(SIGABRT), "");
+}
+
 #endif
 
 TEST(DEATHTEST, sprintf_fortified) {
@@ -456,6 +490,20 @@
   ASSERT_EXIT(snprintf(bufb, n, "%s", bufa), testing::KilledBySignal(SIGABRT), "");
 }
 
+TEST(DEATHTEST, bzero_fortified) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  char buf[10];
+  memcpy(buf, "0123456789", sizeof(buf));
+  size_t n = atoi("11");
+  ASSERT_EXIT(bzero(buf, n), testing::KilledBySignal(SIGABRT), "");
+}
+
+TEST(DEATHTEST, umask_fortified) {
+  ::testing::FLAGS_gtest_death_test_style = "threadsafe";
+  mode_t mask = atoi("1023");  // 01777 in octal
+  ASSERT_EXIT(umask(mask), testing::KilledBySignal(SIGABRT), "");
+}
+
 extern "C" char* __strncat_chk(char*, const char*, size_t, size_t);
 extern "C" char* __strcat_chk(char*, const char*, size_t);