diff --git a/tests/draft-next/optional/format/hostname.json b/tests/draft-next/optional/format/hostname.json
index bfb30636..f4819efa 100644
--- a/tests/draft-next/optional/format/hostname.json
+++ b/tests/draft-next/optional/format/hostname.json
@@ -120,6 +120,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft-next/optional/format/idn-hostname.json b/tests/draft-next/optional/format/idn-hostname.json
index 2524d27b..9abe2d93 100644
--- a/tests/draft-next/optional/format/idn-hostname.json
+++ b/tests/draft-next/optional/format/idn-hostname.json
@@ -326,6 +326,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft2019-09/optional/format/hostname.json b/tests/draft2019-09/optional/format/hostname.json
index f3b7181c..9db7c967 100644
--- a/tests/draft2019-09/optional/format/hostname.json
+++ b/tests/draft2019-09/optional/format/hostname.json
@@ -120,6 +120,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft2019-09/optional/format/idn-hostname.json b/tests/draft2019-09/optional/format/idn-hostname.json
index e8649ec2..05bff0df 100644
--- a/tests/draft2019-09/optional/format/idn-hostname.json
+++ b/tests/draft2019-09/optional/format/idn-hostname.json
@@ -326,6 +326,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft2020-12/optional/format/hostname.json b/tests/draft2020-12/optional/format/hostname.json
index 41418dd4..0e00af2c 100644
--- a/tests/draft2020-12/optional/format/hostname.json
+++ b/tests/draft2020-12/optional/format/hostname.json
@@ -120,6 +120,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft2020-12/optional/format/idn-hostname.json b/tests/draft2020-12/optional/format/idn-hostname.json
index 1df732af..30a0f494 100644
--- a/tests/draft2020-12/optional/format/idn-hostname.json
+++ b/tests/draft2020-12/optional/format/idn-hostname.json
@@ -326,6 +326,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft3/optional/format/host-name.json b/tests/draft3/optional/format/host-name.json
index d418f376..9a75c3c2 100644
--- a/tests/draft3/optional/format/host-name.json
+++ b/tests/draft3/optional/format/host-name.json
@@ -57,6 +57,11 @@
                 "description": "exceeds maximum label length",
                 "data": "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijkl.com",
                 "valid": false
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft4/optional/format/hostname.json b/tests/draft4/optional/format/hostname.json
index a8ecd194..d7c72a7f 100644
--- a/tests/draft4/optional/format/hostname.json
+++ b/tests/draft4/optional/format/hostname.json
@@ -112,6 +112,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft6/optional/format/hostname.json b/tests/draft6/optional/format/hostname.json
index a8ecd194..d7c72a7f 100644
--- a/tests/draft6/optional/format/hostname.json
+++ b/tests/draft6/optional/format/hostname.json
@@ -112,6 +112,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft7/optional/format/hostname.json b/tests/draft7/optional/format/hostname.json
index a8ecd194..d7c72a7f 100644
--- a/tests/draft7/optional/format/hostname.json
+++ b/tests/draft7/optional/format/hostname.json
@@ -112,6 +112,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }
diff --git a/tests/draft7/optional/format/idn-hostname.json b/tests/draft7/optional/format/idn-hostname.json
index 76b35619..068470ea 100644
--- a/tests/draft7/optional/format/idn-hostname.json
+++ b/tests/draft7/optional/format/idn-hostname.json
@@ -318,6 +318,11 @@
                 "description": "single label ending with digit",
                 "data": "hostnam3",
                 "valid": true
+            },
+            {
+                "description": "empty string",
+                "data": "",
+                "valid": false
             }
         ]
     }