diff --git a/lib/hx509/error.c b/lib/hx509/error.c
index f44627e90..32c92cf1b 100644
--- a/lib/hx509/error.c
+++ b/lib/hx509/error.c
@@ -153,9 +153,9 @@ hx509_get_error_string(hx509_context context, int error_code)
 
     s = heim_error_copy_string(msg);
     if (s) {
-	str = heim_string_get_utf8(s);
-	if (str)
-	    str = strdup(str);
+	const char *cstr = heim_string_get_utf8(s);
+	if (cstr)
+	    str = strdup(cstr);
 	heim_release(s);
     }
     return str;