diff --git a/base/include/base/strings.h b/base/include/base/strings.h
index 638f845..20da144 100644
--- a/base/include/base/strings.h
+++ b/base/include/base/strings.h
@@ -36,8 +36,8 @@
 std::string Trim(const std::string& s);
 
 // Joins a container of things into a single string, using the given separator.
-template <typename ContainerT>
-std::string Join(const ContainerT& things, char separator) {
+template <typename ContainerT, typename SeparatorT>
+std::string Join(const ContainerT& things, SeparatorT separator) {
   if (things.empty()) {
     return "";
   }
@@ -53,6 +53,8 @@
 // We instantiate the common cases in strings.cpp.
 extern template std::string Join(const std::vector<std::string>&, char);
 extern template std::string Join(const std::vector<const char*>&, char);
+extern template std::string Join(const std::vector<std::string>&, const std::string&);
+extern template std::string Join(const std::vector<const char*>&, const std::string&);
 
 // Tests whether 's' starts with 'prefix'.
 bool StartsWith(const std::string& s, const char* prefix);
diff --git a/base/strings.cpp b/base/strings.cpp
index bac983b..d687e3c 100644
--- a/base/strings.cpp
+++ b/base/strings.cpp
@@ -83,6 +83,8 @@
 // aid compile time and binary size.
 template std::string Join(const std::vector<std::string>&, char);
 template std::string Join(const std::vector<const char*>&, char);
+template std::string Join(const std::vector<std::string>&, const std::string&);
+template std::string Join(const std::vector<const char*>&, const std::string&);
 
 bool StartsWith(const std::string& s, const char* prefix) {
   return s.compare(0, strlen(prefix), prefix) == 0;