diff --git a/libc/private/kernel_sigset_t.h b/libc/private/kernel_sigset_t.h
new file mode 100644
index 0000000..733a842
--- /dev/null
+++ b/libc/private/kernel_sigset_t.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef LIBC_PRIVATE_KERNEL_SIGSET_T_H_
+#define LIBC_PRIVATE_KERNEL_SIGSET_T_H_
+
+// Our sigset_t is wrong for ARM and x86. It's 32-bit but the kernel expects 64 bits.
+// This means we can't support real-time signals correctly until we can change the ABI.
+// In the meantime, we can use this union to pass an appropriately-sized block of memory
+// to the kernel, at the cost of not being able to refer to real-time signals.
+union kernel_sigset_t {
+  kernel_sigset_t() {
+    clear();
+  }
+
+  kernel_sigset_t(const sigset_t* value) {
+    clear();
+    set(value);
+  }
+
+  void clear() {
+    memset(this, 0, sizeof(*this));
+  }
+
+  void set(const sigset_t* value) {
+    bionic = *value;
+  }
+
+  sigset_t* get() {
+    return &bionic;
+  }
+
+  sigset_t bionic;
+#ifndef __mips__
+  uint32_t kernel[2];
+#endif
+};
+
+#endif