diff --git a/.github/workflows/run_test.yml b/.github/workflows/run_test.yml
index 69bad0e20..595c54aad 100644
--- a/.github/workflows/run_test.yml
+++ b/.github/workflows/run_test.yml
@@ -1,4 +1,4 @@
-name: simple_calculator unit test
+name: simple_calculator, max_subarray_sum, and two_sum unit test
   
 on: [push]  
   
@@ -28,6 +28,7 @@ jobs:
         run: |  
           coverage run -m pytest tests/tests_1b.py -v -s
           coverage run -m pytest tests/tests_1c.py -v -s
+          coverage run -m pytest tests/tests_1d.py -v -s
       - name: Generate Coverage Report  
         run: |  
           coverage report -m
\ No newline at end of file
diff --git a/labs/lab_1/lab_1d.py b/labs/lab_1/lab_1d.py
index ade4b4a8c..1506810a6 100644
--- a/labs/lab_1/lab_1d.py
+++ b/labs/lab_1/lab_1d.py
@@ -23,7 +23,7 @@ def two_sum(nums: list[int], target: int) -> list[int]:
 
     num_to_index = {}
     for index, num in enumerate(nums):
-        complement = target + num
+        complement = target - num
         if complement in num_to_index:
             return [num_to_index[complement], index]
         num_to_index[num] = index
diff --git a/tests/tests_1c.py b/tests/tests_1c.py
index 306242ae7..f6a08f6d7 100644
--- a/tests/tests_1c.py
+++ b/tests/tests_1c.py
@@ -1,7 +1,7 @@
 """
-tests_1b.py
+tests_1c.py
 
-This module contains unit tests for the max_subarray_sum function defined in lab_1b.py.
+This module contains unit tests for the max_subarray_sum function defined in lab_1c.py.
 """
 
 import pytest
diff --git a/tests/tests_1d.py b/tests/tests_1d.py
new file mode 100644
index 000000000..73c5b8c86
--- /dev/null
+++ b/tests/tests_1d.py
@@ -0,0 +1,17 @@
+"""
+tests_1d.py
+
+This module contains unit tests for the two_sum function defined in lab_1d.py.
+"""
+
+import pytest
+from labs.lab_1.lab_1d import two_sum
+
+def test():
+    assert two_sum([2, 7, 11, 15], 18) == [1, 2]
+    assert two_sum([2, 7, 11, 15], 26) == [2, 3]
+    assert two_sum([2, 7, 11, 15], 22) == [1, 3]
+
+
+if __name__ == "__main__":
+    pytest.main()
\ No newline at end of file