diff --git a/libc/bionic/strerror_r.cpp b/libc/bionic/strerror_r.cpp
index a00ebe5..e6a3975 100644
--- a/libc/bionic/strerror_r.cpp
+++ b/libc/bionic/strerror_r.cpp
@@ -27,7 +27,7 @@
   { 0, NULL }
 };
 
-extern "C" const char* __strerror_lookup(int error_number) {
+extern "C" __LIBC_HIDDEN__ const char* __strerror_lookup(int error_number) {
   return __code_string_lookup(_sys_error_strings, error_number);
 }
 
@@ -37,7 +37,7 @@
   { 0, NULL }
 };
 
-extern "C" const char* __strsignal_lookup(int signal_number) {
+extern "C" __LIBC_HIDDEN__ const char* __strsignal_lookup(int signal_number) {
   return __code_string_lookup(_sys_signal_strings, signal_number);
 }
 
@@ -60,7 +60,7 @@
   return 0;
 }
 
-extern "C" const char* __strsignal(int signal_number, char* buf, size_t buf_len) {
+extern "C" __LIBC_HIDDEN__ const char* __strsignal(int signal_number, char* buf, size_t buf_len) {
   const char* signal_name = __strsignal_lookup(signal_number);
   if (signal_name != NULL) {
     return signal_name;