diff --git a/src/File.cc b/src/File.cc
index 19a0190..c0c47e3 100644
--- a/src/File.cc
+++ b/src/File.cc
@@ -207,8 +207,11 @@ void File::parse(const std::filesystem::path& filename) {
 
                 case Tokenizer::TokenType::INCLUDE: {
                     auto name = tokenizer.expect(Tokenizer::TokenType::WORD, Tokenizer::Skip::SPACE);
-                    includes.insert(name.string());
-                    tokenizers.emplace_back(name.string());
+                    auto include_filename = Filename(Filename::Type::SOURCE, name.string());
+                    auto result = ResolveResult();
+                    include_filename.resolve(ResolveContext(*this, result));
+                    includes.insert(include_filename);
+                    tokenizers.emplace_back(include_filename.full_name().string());
                     break;
                 }
 
@@ -295,6 +298,7 @@ void File::parse_subninja(Tokenizer& tokenizer) {
 
 void File::add_generator_build(std::vector<Filename>& ninja_outputs, std::vector<Filename>& ninja_inputs) const { // NOLINT(misc-no-recursion)
     ninja_outputs.emplace_back(Filename::Type::BUILD, build_filename.string());
+    ninja_inputs.insert(ninja_inputs.end(), includes.begin(), includes.end());
     ninja_inputs.emplace_back(Filename::Type::COMPLETE, source_filename.string());
     for (const auto& file: subfiles) {
         file->add_generator_build(ninja_outputs, ninja_inputs);
diff --git a/src/File.h b/src/File.h
index c5e1151..d03acd9 100644
--- a/src/File.h
+++ b/src/File.h
@@ -83,7 +83,7 @@ class File: public Scope {
     std::filesystem::path build_filename;
 
     std::unordered_set<std::string> outputs;
-    std::set<std::string> includes;
+    std::set<Filename> includes;
     std::map<std::string, Rule> rules;
     std::map<std::string, Pool> pools;
     std::vector<Build> builds;
diff --git a/src/Filename.cc b/src/Filename.cc
index d4d6c9c..1248ac9 100644
--- a/src/Filename.cc
+++ b/src/Filename.cc
@@ -52,7 +52,9 @@ void Filename::resolve(const ResolveContext& context) {
 
     switch (type) {
         case Type::BUILD:
-            prefix = file->build_directory;
+            if (prefix.empty()) {
+                prefix = file->build_directory;
+            }
             break;
 
         case Type::COMPLETE:
@@ -60,7 +62,9 @@ void Filename::resolve(const ResolveContext& context) {
             break;
 
         case Type::SOURCE:
-            prefix = file->source_directory;
+            if (prefix.empty()) {
+                prefix = file->source_directory;
+            }
             if (!std::filesystem::exists(full_name())) {
                 throw Exception("source file '" + full_name().string() + "' does not exist");
             }
@@ -80,6 +84,13 @@ std::filesystem::path Filename::full_name() const {
     }
 }
 
+bool Filename::operator<(const Filename& other) const {
+    if (type != other.type) {
+        return type < other.type;
+    }
+    return name < other.name;
+}
+
 std::ostream& operator<<(std::ostream& stream, const Filename& file_name) {
     stream << file_name.full_name().generic_string();
     return stream;
diff --git a/src/Filename.h b/src/Filename.h
index 14280ec..f7f523e 100644
--- a/src/Filename.h
+++ b/src/Filename.h
@@ -55,6 +55,10 @@ class Filename {
 
     [[nodiscard]] std::filesystem::path full_name() const;
 
+    // TODO: consider prefix?
+    bool operator<(const Filename& other) const;
+    bool operator==(const Filename& other) const {return type == other.type && name == other.name;}
+
     Type type{Type::UNKNOWN};
     std::string name;
     std::filesystem::path prefix;