diff --git a/docs/change_log/release-3.1.md b/docs/change_log/release-3.1.md
index 7959364ce..b05cd230d 100644
--- a/docs/change_log/release-3.1.md
+++ b/docs/change_log/release-3.1.md
@@ -37,6 +37,7 @@ The following new features have been included in the release:
 
 The following bug fixes are included in the 3.1 release:
 
+* Update CLI to support PyYAML 5.1.
 * Overlapping raw HTML matches no longer leave placeholders behind (#458).
 * Emphasis patterns now recognize newline characters as whitespace (#783).
 * Version format had been updated to be PEP 440 compliant (#736).
diff --git a/markdown/__main__.py b/markdown/__main__.py
index 38d08fe06..43e486c9a 100644
--- a/markdown/__main__.py
+++ b/markdown/__main__.py
@@ -26,9 +26,17 @@
 import warnings
 import markdown
 try:
-    import yaml
+    # We use `unsafe_load` because users may need to pass in actual Python
+    # objects. As this is only available from the CLI, the user has much
+    # worse problems if an attacker can use this as an attach vector.
+    from yaml import unsafe_load as yaml_load
 except ImportError:  # pragma: no cover
-    import json as yaml
+    try:
+        # Fall back to PyYAML <5.1
+        from yaml import load as yaml_load
+    except ImportError:
+        # Fall back to JSON
+        from json import load as yaml_load
 
 import logging
 from logging import DEBUG, WARNING, CRITICAL
@@ -97,7 +105,7 @@ def parse_options(args=None, values=None):
             options.configfile, mode="r", encoding=options.encoding
         ) as fp:
             try:
-                extension_configs = yaml.load(fp)
+                extension_configs = yaml_load(fp)
             except Exception as e:
                 message = "Failed parsing extension config file: %s" % \
                           options.configfile