diff --git a/CHANGELOG.md b/CHANGELOG.md
index 812d4b65e..2e5adf53d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,9 +22,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
   This fixes a bug in v0.20.0 where provenance entries from an extensible enumerator could _only_ be JSON objects, instead of arbitrary JSON values as claimed by the documentation.
 
+### Fixes
+- The `Blynk Organization Client Credentials` rule now has a non-varying number of capture groups
 
 ### Changes
 - The `Slack Bot Token` rule has been modified to match additional cases.
+- The `rules check` command now more thoroughly checks the number of capture groups of each rule
 
 ### Additions
 - New rules have been added:
diff --git a/crates/noseyparker-cli/src/cmd_rules/cmd_rules_check.rs b/crates/noseyparker-cli/src/cmd_rules/cmd_rules_check.rs
index bbea87082..c55c49666 100644
--- a/crates/noseyparker-cli/src/cmd_rules/cmd_rules_check.rs
+++ b/crates/noseyparker-cli/src/cmd_rules/cmd_rules_check.rs
@@ -223,9 +223,16 @@ fn check_rule(rule: &Rule, args: &RulesCheckArgs) -> Result<CheckStats> {
         }
         Ok(pat) => {
             // Check that the rule has at least one capture group
-            if pat.captures_len() <= 1 {
-                error!("Rule has no capture groups");
-                num_errors += 1;
+            match pat.static_captures_len() {
+                Some(0) => {
+                    error!("Rule has no capture groups");
+                    num_errors += 1;
+                }
+                Some(_len) => {}
+                None => {
+                    error!("Rule has a variable number of capture groups");
+                    num_errors += 1;
+                }
             }
 
             let mut num_succeeded = 0;
diff --git a/crates/noseyparker-cli/tests/rules/snapshots/test_noseyparker__rules__rules_list_json-2.snap b/crates/noseyparker-cli/tests/rules/snapshots/test_noseyparker__rules__rules_list_json-2.snap
index d0f02b923..0d08f70f6 100644
--- a/crates/noseyparker-cli/tests/rules/snapshots/test_noseyparker__rules__rules_list_json-2.snap
+++ b/crates/noseyparker-cli/tests/rules/snapshots/test_noseyparker__rules__rules_list_json-2.snap
@@ -553,12 +553,12 @@ expression: stdout
     },
     {
       "id": "np.blynk.9",
-      "structural_id": "61027ac6a0bd9260330393485339d3012565b1b0",
+      "structural_id": "c6cec8b505fc62859dde26fd04c1656d6ab79286",
       "name": "Blynk Organization Client Credentials",
       "syntax": {
         "name": "Blynk Organization Client Credentials",
         "id": "np.blynk.9",
-        "pattern": "(?x)\n\\b\n(oa2-client-id_[a-zA-Z0-9_\\-]{32})\n:([a-zA-Z0-9_\\-]{40})\n[\\s\\\\]*https://(fra1\\.|lon1\\.|ny3\\.|sgp1\\.|blr1\\.)*blynk\\.cloud/oauth2\n",
+        "pattern": "(?x)\n\\b\n(oa2-client-id_[a-zA-Z0-9_\\-]{32})\n:([a-zA-Z0-9_\\-]{40})\n[\\s\\\\]*https://(?:fra1\\.|lon1\\.|ny3\\.|sgp1\\.|blr1\\.)*blynk\\.cloud/oauth2\n",
         "description": null,
         "examples": [
           "curl -X POST -u oa2-client-id_zmNtW-D0Toqpz4AZnBLCIlklBrz9ynU-:5uC5Y4Mcvdl5rB56rBmxnvB4DZgiIpcyTPbOoEWp https://fra1.blynk.cloud/oauth2/token?grant_type=client_credentials",
diff --git a/crates/noseyparker/data/default/builtin/rules/blynk.yml b/crates/noseyparker/data/default/builtin/rules/blynk.yml
index ed885d28d..a6f6fbcf1 100644
--- a/crates/noseyparker/data/default/builtin/rules/blynk.yml
+++ b/crates/noseyparker/data/default/builtin/rules/blynk.yml
@@ -105,7 +105,7 @@ rules:
     \b
     (oa2-client-id_[a-zA-Z0-9_\-]{32})
     :([a-zA-Z0-9_\-]{40})
-    [\s\\]*https://(fra1\.|lon1\.|ny3\.|sgp1\.|blr1\.)*blynk\.cloud/oauth2
+    [\s\\]*https://(?:fra1\.|lon1\.|ny3\.|sgp1\.|blr1\.)*blynk\.cloud/oauth2
 
   categories:
   - api