diff --git a/libc/arch-x86/atom/string/sse2-memset-atom.S b/libc/arch-x86/atom/string/sse2-memset-atom.S
index 30fb3f1..e03cd1a 100644
--- a/libc/arch-x86/atom/string/sse2-memset-atom.S
+++ b/libc/arch-x86/atom/string/sse2-memset-atom.S
@@ -113,11 +113,12 @@
 #endif
 
 ENTRY(__memset_chk)
-  movl LEN(%esp), %ecx
-  cmpl %ecx, CHK_DST_LEN(%esp)
-  jbe memset
+  ENTRANCE
 
-  jmp __memset_chk_fail
+  movl LEN(%esp), %ecx
+  cmpl CHK_DST_LEN(%esp), %ecx
+  ja __memset_chk_fail
+  jmp L(memset_length_loaded)
 END(__memset_chk)
 
 	.section .text.sse2,"ax",@progbits
@@ -126,6 +127,7 @@
 	ENTRANCE
 
 	movl	LEN(%esp), %ecx
+L(memset_length_loaded):
 	movzbl	CHR(%esp), %eax
 	movb	%al, %ah
 	/* Fill the whole EAX with pattern.  */
diff --git a/libc/arch-x86/silvermont/string/sse2-memset-slm.S b/libc/arch-x86/silvermont/string/sse2-memset-slm.S
index 0718fa7..f5182ba 100644
--- a/libc/arch-x86/silvermont/string/sse2-memset-slm.S
+++ b/libc/arch-x86/silvermont/string/sse2-memset-slm.S
@@ -113,11 +113,12 @@
 #endif
 
 ENTRY(__memset_chk)
-  movl LEN(%esp), %ecx
-  cmpl %ecx, CHK_DST_LEN(%esp)
-  jbe memset
+  ENTRANCE
 
-  jmp __memset_chk_fail
+  movl LEN(%esp), %ecx
+  cmpl CHK_DST_LEN(%esp), %ecx
+  ja __memset_chk_fail
+  jmp L(memset_length_loaded)
 END(__memset_chk)
 
 	.section .text.sse2,"ax",@progbits
@@ -126,6 +127,7 @@
 	ENTRANCE
 
 	movl	LEN(%esp), %ecx
+L(memset_length_loaded):
 	cmp	$0, %ecx
 	ja	L(1byteormore)
 	SETRTNVAL
diff --git a/libc/bionic/clone.cpp b/libc/bionic/clone.cpp
index 9b5c9e7..af63977 100644
--- a/libc/bionic/clone.cpp
+++ b/libc/bionic/clone.cpp
@@ -47,6 +47,11 @@
   void* new_tls = NULL;
   int* child_tid = NULL;
 
+  if (!child_stack) {
+    errno = EINVAL;
+    return -1;
+  }
+
   // Extract any optional parameters required by the flags.
   va_list args;
   va_start(args, arg);
diff --git a/libc/bionic/epoll_create.cpp b/libc/bionic/epoll_create.cpp
index 1dfafa8..74f664f 100644
--- a/libc/bionic/epoll_create.cpp
+++ b/libc/bionic/epoll_create.cpp
@@ -26,8 +26,13 @@
  * SUCH DAMAGE.
  */
 
+#include <errno.h>
 #include <sys/epoll.h>
 
-int epoll_create(int /*obsolete_size*/) {
+int epoll_create(int size) {
+  if (size <= 0) {
+    errno = EINVAL;
+    return -1;
+  }
   return epoll_create1(0);
 }
diff --git a/tests/getauxval_test.cpp b/tests/getauxval_test.cpp
index 6499f89..54458c4 100644
--- a/tests/getauxval_test.cpp
+++ b/tests/getauxval_test.cpp
@@ -67,7 +67,11 @@
   // If this test fails, apps that use getauxval to decide at runtime whether crypto hardware is
   // available will incorrectly assume that it isn't, and will have really bad performance.
   // If this test fails, ensure that you've enabled COMPAT_BINFMT_ELF in your kernel configuration.
-  ASSERT_NE(0UL, getauxval(AT_HWCAP2)) << "kernel not reporting AT_HWCAP2 to 32-bit ARM process";
+  // Note that 0 ("I don't support any of these things") is a legitimate response --- we need
+  // to check errno to see whether we got a "true" 0 or a "not found" 0.
+  errno = 0;
+  getauxval(AT_HWCAP2);
+  ASSERT_EQ(0, errno) << "kernel not reporting AT_HWCAP2 to 32-bit ARM process";
 #else
   GTEST_LOG_(INFO) << "This test is only meaningful for 32-bit ARM code.\n";
 #endif
diff --git a/tests/sched_test.cpp b/tests/sched_test.cpp
index caf4c65..92d6c26 100644
--- a/tests/sched_test.cpp
+++ b/tests/sched_test.cpp
@@ -21,12 +21,12 @@
 #include <sys/types.h>
 #include <sys/wait.h>
 
-#if defined(__BIONIC__)
 static int child_fn(void* i_ptr) {
   *reinterpret_cast<int*>(i_ptr) = 42;
   return 123;
 }
 
+#if defined(__BIONIC__)
 TEST(sched, clone) {
   void* child_stack[1024];
 
@@ -59,6 +59,13 @@
   ASSERT_EQ(EINVAL, errno);
 }
 
+TEST(sched, clone_null_child_stack) {
+  int i = 0;
+  errno = 0;
+  ASSERT_EQ(-1, clone(child_fn, nullptr, CLONE_VM, &i));
+  ASSERT_EQ(EINVAL, errno);
+}
+
 TEST(sched, cpu_set) {
   cpu_set_t set;
 
diff --git a/tests/sys_epoll_test.cpp b/tests/sys_epoll_test.cpp
index 6e7a807..f6be4af 100644
--- a/tests/sys_epoll_test.cpp
+++ b/tests/sys_epoll_test.cpp
@@ -40,6 +40,12 @@
   ASSERT_EQ(0, epoll_pwait(epoll_fd, events, 1, 1, &ss));
 }
 
+TEST(sys_epoll, epoll_create_invalid_size) {
+  errno = 0;
+  ASSERT_EQ(-1, epoll_create(0));
+  ASSERT_EQ(EINVAL, errno);
+}
+
 TEST(sys_epoll, epoll_event_data) {
   int epoll_fd = epoll_create(1);
   ASSERT_NE(-1, epoll_fd) << strerror(errno);