diff --git a/libc/stdio/vfprintf.cpp b/libc/stdio/vfprintf.cpp
index 8b247e9..d99d09c 100644
--- a/libc/stdio/vfprintf.cpp
+++ b/libc/stdio/vfprintf.cpp
@@ -453,7 +453,7 @@
       case 'n':
         __fortify_fatal("%%n not allowed on Android");
       case 'm':
-        cp = strerror(caller_errno);
+        cp = strerror_r(caller_errno, buf, sizeof(buf));
         goto string;
       case 'O':
         flags |= LONGINT;
diff --git a/libc/stdio/vfwprintf.cpp b/libc/stdio/vfwprintf.cpp
index 19cce17..dd51eec 100644
--- a/libc/stdio/vfwprintf.cpp
+++ b/libc/stdio/vfwprintf.cpp
@@ -439,7 +439,8 @@
         __fortify_fatal("%%n not allowed on Android");
       case 'm':
         free(convbuf);
-        convbuf = helpers::mbsconv(strerror(caller_errno), prec);
+        convbuf = helpers::mbsconv(strerror_r(caller_errno,
+                                              reinterpret_cast<char*>(buf), sizeof(buf)), prec);
         if (convbuf == nullptr) {
             fp->_flags |= __SERR;
             goto error;