diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 31fa175..6825b8c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,7 +17,7 @@ jobs:
       uses: ./
       with:
         working-directory: test
-        target: test
+        target: test1
     - name: Check non-recursive prerequisites
       run: |
         test "${{ steps.non-recursive-prerequisites.outputs.prerequisites }}" = "prereq"
@@ -27,9 +27,20 @@ jobs:
       uses: ./
       with:
         working-directory: test
-        target: test
+        target: test1
         flags: --recursive
     - name: Check recursive prerequisites
       run: |
         test "${{ steps.recursive-prerequisites.outputs.prerequisites }}" = "preprereq1 preprereq2"
         echo ${{ steps.recursive-prerequisites.outputs.hash }}
+    - name: Hash directory prerequisite
+      id: hash-dir-prerequisite
+      uses: ./
+      with:
+        working-directory: test
+        target: test2
+        flags: --recursive
+    - name: Check directory prerequisite hash
+      run: |
+        test "${{ steps.hash-dir-prerequisite.outputs.prerequisites }}" = "dirprereq"
+        test "${{ steps.hash-dir-prerequisite.outputs.hash }}" = "c64a77871513eadd52ec0e278bfbac1db866b77f66ebe91725b378b8bf43e29c"
diff --git a/list-make-prerequisites.py b/list-make-prerequisites.py
index 7836625..650c249 100755
--- a/list-make-prerequisites.py
+++ b/list-make-prerequisites.py
@@ -5,6 +5,7 @@
 from anytree import Node, RenderTree
 import argparse
 import hashlib
+from pathlib import Path
 import re
 import subprocess
 import sys
@@ -137,9 +138,18 @@ def hash_files(file_list):
     # Create a new SHA-256 hash object
     hasher = hashlib.sha256()
 
+    # If any prerequisite is a directory, replace it with its (recursive) contents
+    expanded_file_list = []
     for file_name in file_list:
-        # Open each file in binary mode
-        try:        
+        file = Path(file_name)
+        if file.is_dir():
+            expanded_file_list.extend([str(f) for f in file.rglob('*') if f.is_file()])
+        else:
+            expanded_file_list.append(file_name)
+
+    # Hash file contents
+    for file_name in expanded_file_list:
+        try:
             with open(file_name, 'rb') as f:
                 # Read the file content in chunks to avoid memory issues with large files
                 while chunk := f.read(8192):  # 8192 bytes per chunk
diff --git a/test/Makefile b/test/Makefile
index 750deca..f1db02f 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -1,6 +1,8 @@
-test: prereq
+test1: prereq
 	cp $< $@
 
 prereq: preprereq1 preprereq2
 	cp $< $@
 	cat preprereq2 >> $@
+
+test2: dirprereq
\ No newline at end of file
diff --git a/test/dirprereq/dir/prereq.txt b/test/dirprereq/dir/prereq.txt
new file mode 100644
index 0000000..96638e5
--- /dev/null
+++ b/test/dirprereq/dir/prereq.txt
@@ -0,0 +1 @@
+prereq
\ No newline at end of file