diff --git a/src/utils/cpputils/url.cc b/src/utils/cpputils/url.cc
index c1e5d27f5340af3fd3db272efea8a42e17ab1fa0..607c019426ae3e88784b85ccfcd54642cafe16f0 100644
--- a/src/utils/cpputils/url.cc
+++ b/src/utils/cpputils/url.cc
@@ -517,7 +517,7 @@ std::string ResolvePath(const std::string &base, const std::string &ref)
     for (auto it = dst.begin(); it != dst.end(); ++it) {
         ret += (*it + ((it + 1 != dst.end()) ? "/" : ""));
     }
-    if (ret.at(0) == '/') {
+    if (ret.size() > 0 && ret.at(0) == '/') {
         ret.erase(ret.begin());
     }
     return "/" + ret;