diff --git a/libc/bionic/brk.cpp b/libc/bionic/brk.cpp
index 4e46193..a8c078b 100644
--- a/libc/bionic/brk.cpp
+++ b/libc/bionic/brk.cpp
@@ -35,6 +35,8 @@
 void* __bionic_brk; // Accidentally exported by the NDK.
 #endif
 
+extern "C" void* __brk(void* __addr);
+
 int brk(void* end_data) {
   __bionic_brk = __brk(end_data);
   if (__bionic_brk < end_data) {
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index 6b5ef76..71764ae 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -204,7 +204,6 @@
 int gethostname(char* __name, size_t __len);
 int sethostname(const char* __name, size_t __len) __INTRODUCED_IN(23);
 
-extern void* __brk(void* __addr);
 extern int brk(void* __addr);
 extern void* sbrk(ptrdiff_t __increment);