diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 38c18b5ccf..50844cf58b 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,3 +12,8 @@ repos:
   hooks:
     - id: shfmt
       args: ["-w", "-i", "4", "-ci"]
+
+- repo: https://github.com/pre-commit/mirrors-yapf
+  rev: v0.31.0
+  hooks:
+  - id: yapf
diff --git a/.style.yapf b/.style.yapf
new file mode 100644
index 0000000000..b05085101b
--- /dev/null
+++ b/.style.yapf
@@ -0,0 +1,2 @@
+[style]
+column_limit=100
diff --git a/src/make_dbg_constants.py b/src/make_dbg_constants.py
index 51a9c4c3b7..3b5d7f2da6 100644
--- a/src/make_dbg_constants.py
+++ b/src/make_dbg_constants.py
@@ -53,11 +53,15 @@ namespace zeek::detail {\n
 void init_global_dbg_constants () {
 ''' % inputfile
 
+
 def outputrecord():
     global init_str, enum_str
 
     if dbginfo["names"]:
-        dbginfo["name_init"] = "const char * const names[] = {\n\t\t\t%s\n\t\t};\n" % ",\n\t\t\t".join(dbginfo["names"])
+        dbginfo["name_init"] = "const char * const names[] = {\n"\
+                               "\t\t\t%s\n"\
+                               "\t\t};\n" \
+                               % ",\n\t\t\t".join(dbginfo["names"])
     else:
         dbginfo["name_init"] = "const char * const names[] = { };\n"
 
@@ -68,16 +72,25 @@ def outputrecord():
 
     enum_str += "\t%s,\n" % dbginfo["cmd"]
 
+
 def initdbginfo():
-    return {"cmd": "", "name_init": "", "num_names": 0, "names": [],
-            "resume": "false", "help": "", "repeatable": "false"}
+    return {
+        "cmd": "",
+        "name_init": "",
+        "num_names": 0,
+        "names": [],
+        "resume": "false",
+        "help": "",
+        "repeatable": "false"
+    }
+
 
 dbginfo = initdbginfo()
 
 inputf = open(inputfile, "r")
 for line in inputf:
     line = line.strip()
-    if not line or line.startswith("//"):	# skip empty lines and comments
+    if not line or line.startswith("//"):  # skip empty lines and comments
         continue
 
     fields = line.split(":", 1)
@@ -95,9 +108,9 @@ for line in inputf:
         dbginfo[f1] = f2
     elif f1 == "names":
         # put quotes around the strings
-        dbginfo[f1] = [ '"%s"' % n for n in f2.split() ]
+        dbginfo[f1] = ['"%s"' % n for n in f2.split()]
     elif f1 == "help":
-        dbginfo[f1] = f2.replace('"', '\\"') # escape quotation marks
+        dbginfo[f1] = f2.replace('"', '\\"')  # escape quotation marks
     elif f1 in ("resume", "repeatable"):
         dbginfo[f1] = f2
     else:
diff --git a/testing/scripts/coverage-calc b/testing/scripts/coverage-calc
index 016cfff5c4..0d5f2d8269 100755
--- a/testing/scripts/coverage-calc
+++ b/testing/scripts/coverage-calc
@@ -56,4 +56,5 @@ for k in stats:
         num_covered += 1
 
 if len(stats) > 0:
-    print("%s/%s (%.1f%%) Zeek script statements covered." % (num_covered, len(stats), float(num_covered)/len(stats)*100))
+    print("%s/%s (%.1f%%) Zeek script statements covered." %
+          (num_covered, len(stats), float(num_covered) / len(stats) * 100))
diff --git a/testing/scripts/httpd.py b/testing/scripts/httpd.py
index 7ecfb636e9..00d7143165 100755
--- a/testing/scripts/httpd.py
+++ b/testing/scripts/httpd.py
@@ -2,8 +2,8 @@
 
 import http.server as BaseHTTPServer
 
-class MyRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
 
+class MyRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
     def do_GET(self):
         self.send_response(200)
         self.send_header("Content-type", "text/plain")
@@ -34,17 +34,21 @@ class MyRequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
 if __name__ == "__main__":
     from optparse import OptionParser
     p = OptionParser()
-    p.add_option("-a", "--addr", type="string", default="localhost",
+    p.add_option("-a",
+                 "--addr",
+                 type="string",
+                 default="localhost",
                  help=("listen on given address (numeric IP or host name), "
                        "an empty string (the default) means INADDR_ANY"))
-    p.add_option("-p", "--port", type="int", default=32123,
-                 help="listen on given TCP port number")
-    p.add_option("-m", "--max", type="int", default=-1,
+    p.add_option("-p", "--port", type="int", default=32123, help="listen on given TCP port number")
+    p.add_option("-m",
+                 "--max",
+                 type="int",
+                 default=-1,
                  help="max number of requests to respond to, -1 means no max")
     options, args = p.parse_args()
 
-    httpd = BaseHTTPServer.HTTPServer((options.addr, options.port),
-                                      MyRequestHandler)
+    httpd = BaseHTTPServer.HTTPServer((options.addr, options.port), MyRequestHandler)
     if options.max == -1:
         httpd.serve_forever()
     else: