diff --git a/Makefile b/Makefile
index 0ef7cb612..9fc7c2499 100644
--- a/Makefile
+++ b/Makefile
@@ -93,4 +93,5 @@ review:
 	@read -p "Enter content path: " path; read -p "Enter max line length (default: 100): " line_length; \
 	if [ -z "$$path" ]; then echo "Error: Path cannot be empty"; exit 1; fi; \
 	if [ -z "$$line_length" ]; then line_length=100; fi; \
-	python tests/main.py -e line-too-long -e early-line-breaks --max-line-length=$$line_length $(SOURCE_DIR)/$$path
+	export REVIEW=1; \
+	python tests/main.py --max-line-length=$$line_length $(SOURCE_DIR)/$$path
diff --git a/tests/checkers/resource_files.py b/tests/checkers/resource_files.py
index 49f904d62..576fda893 100644
--- a/tests/checkers/resource_files.py
+++ b/tests/checkers/resource_files.py
@@ -1,5 +1,6 @@
 from pathlib import Path
 
+from PIL import Image
 import sphinxlint
 
 
@@ -7,6 +8,10 @@ MAX_IMAGE_SIZES = {  # in bytes
     '.png': 505000,
     '.gif': 2100000,
 }
+MODE_TO_BPP = {
+    '1': 1, 'L': 8, 'P': 8, 'RGB': 24, 'RGBA': 32, 'CMYK': 32, 'YCbCr': 24, 'I': 32, 'F': 32
+}
+
 
 def log_error(file, line, msg, checker_name):
     """ Log an error in sphinx-lint's log format to ease the processing of linting errors on Runbot.
@@ -28,6 +33,29 @@ def check_image_size(file):
             'image-size',
         )
 
+def check_image_color_depth(file):
+    """ Check that PNG images are compressed to 8-bit color depth with PNGQuant. """
+    file_path = Path(file)
+    if file_path.suffix.lower() == '.png':
+        data = Image.open(file)
+        bpp = MODE_TO_BPP[data.mode]
+        if bpp > 8:
+            log_error(
+                file_path,
+                0,
+                f"the file has a color depth of {bpp} instead of 8; compress it with pngquant",
+                'image-color-depth'
+            )
+
+def check_resource_file_name(file_path):
+    """ Check that resource file names use hyphens rather than underscores. """
+    if '_' in file_path.split('/')[-1]:
+        log_error(
+            file_path,
+            0,
+            "the resource file should have hyphens rather than underscores",
+            'resource-file-name'
+        )
 
 @sphinxlint.checker('')
 def check_file_extensions(file, lines, options=None):
diff --git a/tests/checkers/rst_style.py b/tests/checkers/rst_style.py
index 6d2b083af..1e9304a8e 100644
--- a/tests/checkers/rst_style.py
+++ b/tests/checkers/rst_style.py
@@ -128,7 +128,7 @@ def check_early_line_breaks(file, lines, options=None):
                 '#.': lambda x: x.split('#. ', 1)[0],
                 'default': lambda x: x.split(' ', 1)[0]
             }
-            return next_line_dict.get(next_line_.lstrip()[:2], next_line_dict["default"])(
+            return next_line_dict.get(next_line_.lstrip()[:2], next_line_dict['default'])(
                 next_line_.lstrip()
             )
         else:
@@ -141,7 +141,7 @@ def check_early_line_breaks(file, lines, options=None):
                 and is_valid_line(next_line, ('+', '|', '- ', '* ', '#. '))
             ):
                 current_line_remaining_space = options.max_line_length - len(line)
-                next_line_first_word = get_next_line_first_word(next_line)
+                next_line_first_word = get_next_line_first_word(next_line).rstrip()
                 if current_line_remaining_space > len(next_line_first_word):
                     yield lno + 1, f"consider moving \"{next_line_first_word}\" to line {lno + 1}"
 
diff --git a/tests/main.py b/tests/main.py
index 198202252..778c35be3 100644
--- a/tests/main.py
+++ b/tests/main.py
@@ -1,3 +1,5 @@
+import argparse
+import os
 import re
 import sys
 from itertools import chain
@@ -15,11 +17,18 @@ CUSTOM_RST_DIRECTIVES = [
     'tab', 'tabs', 'group-tab', 'code-tab',  # sphinx_tabs
 ]
 
+ADDITIONAL_CHECKERS = [
+    checkers.resource_files.check_image_size,
+    checkers.resource_files.check_resource_file_name,
+]
+
 
 def run_additional_checks(argv=None):
     _enabled_checkers, args = sphinxlint.parse_args(argv)
     for path in chain.from_iterable(sphinxlint.walk(path, args.ignore) for path in args.paths):
-        checkers.resource_files.check_image_size(path)
+        if not path.endswith('.rst'):
+            for checker in ADDITIONAL_CHECKERS:
+                checker(path)
 
 
 """
@@ -75,5 +84,9 @@ if __name__ == '__main__':
         'sphinxlint.three_dot_directive_re',
         re.compile(rf'\.\.\. {sphinxlint.ALL_DIRECTIVES}::'),
     ):
-        run_additional_checks()
+        parser = argparse.ArgumentParser()
+        if os.getenv('REVIEW') == '1':  # Enable checkers for `make review`.
+            setattr(sphinxlint.check_line_too_long, 'enabled', True)
+            setattr(checkers.rst_style.check_early_line_breaks, 'enabled', True)
+            ADDITIONAL_CHECKERS.extend([checkers.resource_files.check_image_color_depth])
         sys.exit(sphinxlint.main())
diff --git a/tests/requirements.txt b/tests/requirements.txt
index cd411e530..157404908 100644
--- a/tests/requirements.txt
+++ b/tests/requirements.txt
@@ -1,2 +1,3 @@
+Pillow==9.0.1
 mock==5.0.1
 sphinx-lint==0.6.7