diff --git a/ext/prism/depend b/ext/prism/depend
deleted file mode 100644
index ac0e7a9bb3..0000000000
--- a/ext/prism/depend
+++ /dev/null
@@ -1,2 +0,0 @@
-$(OBJS): $(HDRS) $(ruby_headers)
-$(OBJS): $(srcdir)/../../config.yml
diff --git a/ext/prism/extconf.rb b/ext/prism/extconf.rb
index ae1691c979..ea7cfe963e 100644
--- a/ext/prism/extconf.rb
+++ b/ext/prism/extconf.rb
@@ -122,6 +122,8 @@ def add_libprism_source(path)
   add_libprism_source("$(srcdir)/../../src") +
   add_libprism_source("$(srcdir)/../../src/util")
 
+$headers += Dir["#{$srcdir}/../../include/**/*.h"]
+
 # Finally, we'll create the `Makefile` that is going to be used to configure and
 # build the C extension.
 create_makefile("prism/prism")
diff --git a/prism.gemspec b/prism.gemspec
index 74d5412731..ae5c56a45d 100644
--- a/prism.gemspec
+++ b/prism.gemspec
@@ -42,7 +42,6 @@ Gem::Specification.new do |spec|
     "docs/serialization.md",
     "docs/testing.md",
     "ext/prism/api_node.c",
-    "ext/prism/depend",
     "ext/prism/extconf.rb",
     "ext/prism/extension.c",
     "ext/prism/extension.h",