diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a43f49f..51af4a3 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -35,6 +35,9 @@ jobs:
     - name: Validate against flake8
       run: python -m flake8 pdfplumber tests
 
+    - name: Check type annotations via mypy
+      run: python -m mypy --strict pdfplumber
+
   test:
     needs: lint
     runs-on: ubuntu-latest
diff --git a/Makefile b/Makefile
index dd32b02..373ac23 100644
--- a/Makefile
+++ b/Makefile
@@ -17,13 +17,16 @@ check-black:
 	${PYTHON} -m black --check pdfplumber tests
 
 check-isort:
-	${PYTHON} -m isort --check-only pdfplumber tests
+	${PYTHON} -m isort --profile black --check-only pdfplumber tests
 
 check-flake:
 	${PYTHON} -m flake8 pdfplumber tests
 
-lint: check-flake check-black check-isort
+check-mypy:
+	${PYTHON} -m mypy --strict pdfplumber
+
+lint: check-flake check-mypy check-black check-isort
 
 format:
 	${PYTHON} -m black pdfplumber tests
-	${PYTHON} -m isort pdfplumber tests
+	${PYTHON} -m isort --profile black pdfplumber tests
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 903ba1b..ccfdb15 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -4,3 +4,7 @@ pytest-parallel==0.1.1
 flake8==4.0.1
 black==22.3.0
 isort==5.10.1
+pandas==1.4.2
+mypy==0.942
+pandas-stubs==1.2.0.58
+types-Pillow==9.0.14