diff --git a/gunicorn/http/body.py b/gunicorn/http/body.py
index 78f03214a..3de84c7ca 100644
--- a/gunicorn/http/body.py
+++ b/gunicorn/http/body.py
@@ -91,6 +91,8 @@ def parse_chunk_size(self, unreader, data=None):
             chunk_size = chunk_size.rstrip(b" \t")
         if any(n not in b"0123456789abcdefABCDEF" for n in chunk_size):
             raise InvalidChunkSize(chunk_size)
+        if len(chunk_size) == 0:
+            raise InvalidChunkSize(chunk_size)
         chunk_size = int(chunk_size, 16)
 
         if chunk_size == 0:
diff --git a/tests/requests/invalid/chunked_12.http b/tests/requests/invalid/chunked_12.http
new file mode 100644
index 000000000..7ef164eb3
--- /dev/null
+++ b/tests/requests/invalid/chunked_12.http
@@ -0,0 +1,7 @@
+POST /chunked_no_chunk_size_but_ext HTTP/1.1\r\n
+Transfer-Encoding: chunked\r\n
+\r\n
+ ;foo=bar\r\n
+hello\r\n
+0\r\n
+\r\n
diff --git a/tests/requests/invalid/chunked_12.py b/tests/requests/invalid/chunked_12.py
new file mode 100644
index 000000000..0571e1183
--- /dev/null
+++ b/tests/requests/invalid/chunked_12.py
@@ -0,0 +1,2 @@
+from gunicorn.http.errors import InvalidChunkSize
+request = InvalidChunkSize
diff --git a/tests/requests/invalid/chunked_13.http b/tests/requests/invalid/chunked_13.http
new file mode 100644
index 000000000..6c26ebb85
--- /dev/null
+++ b/tests/requests/invalid/chunked_13.http
@@ -0,0 +1,7 @@
+POST /chunked_no_chunk_size HTTP/1.1\r\n
+Transfer-Encoding: chunked\r\n
+\r\n
+\r\n
+hello\r\n
+0\r\n
+\r\n
diff --git a/tests/requests/invalid/chunked_13.py b/tests/requests/invalid/chunked_13.py
new file mode 100644
index 000000000..0571e1183
--- /dev/null
+++ b/tests/requests/invalid/chunked_13.py
@@ -0,0 +1,2 @@
+from gunicorn.http.errors import InvalidChunkSize
+request = InvalidChunkSize