diff --git a/format-specs/schema.json b/format-specs/schema.json
index 7db7ab0..26cddec 100644
--- a/format-specs/schema.json
+++ b/format-specs/schema.json
@@ -74,7 +74,9 @@
             },
             "covering": {
               "type": "object",
-              "minProperties": 1,
+              "required": [
+                "bbox"
+              ],
               "properties": {
                 "bbox": {
                   "type": "object",
@@ -83,7 +85,7 @@
                     "xmin": {
                       "type": "array",
                       "items": [
-                        { "type": "string" },
+                        { "type": "string", "minLength": 1 },
                         { "const": "xmin" }
                       ],
                       "minItems": 2,
@@ -92,7 +94,7 @@
                     "xmax": {
                       "type": "array",
                       "items": [
-                        { "type": "string" },
+                        { "type": "string", "minLength": 1 },
                         { "const": "xmax" }
                       ],
                       "minItems": 2,
@@ -101,7 +103,7 @@
                     "ymin": {
                       "type": "array",
                       "items": [
-                        { "type": "string" },
+                        { "type": "string", "minLength": 1 },
                         { "const": "ymin" }
                       ],
                       "minItems": 2,
@@ -110,7 +112,7 @@
                     "ymax": {
                       "type": "array",
                       "items": [
-                        { "type": "string" },
+                        { "type": "string", "minLength": 1 },
                         { "const": "ymax" }
                       ],
                       "minItems": 2,
diff --git a/scripts/test_json_schema.py b/scripts/test_json_schema.py
index be0888f..61a1b4b 100644
--- a/scripts/test_json_schema.py
+++ b/scripts/test_json_schema.py
@@ -221,7 +221,6 @@ def get_version() -> str:
     },
 }
 
-
 # Allow "any_column.xmin" etc.
 metadata = copy.deepcopy(metadata_covering_template)
 valid_cases["valid_default_bbox"] = metadata
@@ -235,6 +234,15 @@ def get_version() -> str:
 }
 valid_cases["valid_but_not_bbox_struct_name"] = metadata
 
+metadata = copy.deepcopy(metadata_covering_template)
+metadata["columns"]["geometry"]["covering"]["bbox"] = {
+    "xmin": ["", "xmin"],
+    "ymin": ["", "ymin"],
+    "xmax": ["", "xmax"],
+    "ymax": ["", "ymax"],
+}
+invalid_cases["empty_column_name"] = metadata
+
 metadata = copy.deepcopy(metadata_covering_template)
 metadata["columns"]["geometry"]["covering"]["bbox"]["xmin"] = []
 invalid_cases["xmin_array_length_must_be_2_is_0"] = metadata