diff --git a/src/file.cpp b/src/file.cpp
index 32d4a7c63..46973057a 100644
--- a/src/file.cpp
+++ b/src/file.cpp
@@ -323,7 +323,7 @@ namespace Sass {
     // (2) underscore + given
     // (3) underscore + given + extension
     // (4) given + extension
-    std::vector<Include> resolve_includes(const std::string& root, const std::string& file, const std::vector<std::string>& exts)
+    std::vector<Include> resolve_includes(const std::string& root, const std::string& file, const std::vector<std::string>& exts, const std::vector<std::string>& d_exts)
     {
       std::string filename = join_paths(root, file);
       // split the filename
@@ -350,6 +350,18 @@ namespace Sass {
         abs_path = join_paths(root, rel_path);
         if (file_exists(abs_path)) includes.push_back({{ rel_path, root }, abs_path });
       }
+      // next test d_exts plus underscore
+      for(auto ext : d_exts) {
+        rel_path = join_paths(base, "_" + name + ext);
+        abs_path = join_paths(root, rel_path);
+        if (file_exists(abs_path)) includes.push_back({{ rel_path, root }, abs_path });
+      }
+      // next test plain name with d_exts
+      for(auto ext : d_exts) {
+        rel_path = join_paths(base, name + ext);
+        abs_path = join_paths(root, rel_path);
+        if (file_exists(abs_path)) includes.push_back({{ rel_path, root }, abs_path });
+      }
       // nothing found
       return includes;
     }
diff --git a/src/file.hpp b/src/file.hpp
index 279b9e9f6..759996fa8 100644
--- a/src/file.hpp
+++ b/src/file.hpp
@@ -121,10 +121,12 @@ namespace Sass {
 
   namespace File {
 
-    static std::vector<std::string> defaultExtensions = { ".scss", ".sass", ".css" };
+    static std::vector<std::string> defaultExtensions = { ".scss", ".sass" };
+    static std::vector<std::string> deprecatedExtensions = { ".css" };
 
     std::vector<Include> resolve_includes(const std::string& root, const std::string& file,
-      const std::vector<std::string>& exts = defaultExtensions);
+      const std::vector<std::string>& exts = defaultExtensions,
+      const std::vector<std::string>& d_exts = deprecatedExtensions);
 
   }