diff --git a/coverage/jsonreport.py b/coverage/jsonreport.py
index 18b05b3ac..3db266bd5 100644
--- a/coverage/jsonreport.py
+++ b/coverage/jsonreport.py
@@ -24,7 +24,8 @@
 
 # "Version 1" had no format number at all.
 # 2: add the meta.format field.
-FORMAT_VERSION = 2
+# 3: add region information (functions, classes)
+FORMAT_VERSION = 3
 
 class JsonReporter:
     """A reporter for writing JSON coverage results."""
diff --git a/tests/test_json.py b/tests/test_json.py
index c3ac3b7e8..4a3ba92a5 100644
--- a/tests/test_json.py
+++ b/tests/test_json.py
@@ -98,7 +98,7 @@ def test_branch_coverage(self) -> None:
         expected_result = {
             'meta': {
                 "branch_coverage": True,
-                "format": 2,
+                "format": 3,
                 "show_contexts": False,
             },
             'files': {
@@ -150,7 +150,7 @@ def test_simple_line_coverage(self) -> None:
         expected_result = {
             'meta': {
                 "branch_coverage": False,
-                "format": 2,
+                "format": 3,
                 "show_contexts": False,
             },
             'files': {
@@ -184,7 +184,7 @@ def test_regions_coverage(self) -> None:
         expected_result = {
             "meta": {
                 "branch_coverage": False,
-                "format": 2,
+                "format": 3,
                 "show_contexts": False,
             },
             "files": {
@@ -407,7 +407,7 @@ def test_branch_regions_coverage(self) -> None:
             },
             "meta": {
                 "branch_coverage": True,
-                "format": 2,
+                "format": 3,
                 "show_contexts": False,
             },
             "totals": {
@@ -441,7 +441,7 @@ def run_context_test(self, relative_files: bool) -> None:
         expected_result = {
             'meta': {
                 "branch_coverage": False,
-                "format": 2,
+                "format": 3,
                 "show_contexts": True,
             },
             'files': {