diff --git a/tz.cpp b/tz.cpp
index e84f0fd..377968f 100644
--- a/tz.cpp
+++ b/tz.cpp
@@ -3134,7 +3134,8 @@ current_zone()
         {
             std::ostringstream os;
             char message[128];
-            (void)strerror_r(errno, message, 128);
+            if (strerror_r(errno, message, sizeof(message)) != 0)
+                message[0] = '\0';
             os << "realpath failure: errno = " << errno << "; " << message;
             throw std::runtime_error(os.str());
         }