diff --git a/.github/renovate.json5 b/.github/renovate.json5
index 5fa19c28..7c57943f 100644
--- a/.github/renovate.json5
+++ b/.github/renovate.json5
@@ -63,7 +63,7 @@
       datasourceTemplate: "github-release-attachments",
       packageNameTemplate: "jdx/mise",
       depNameTemplate: "mise",
-      matchStrings: ["jdx/mise-action.*\\n\\s*with:\\s*\\n\\s*version: [\"']?(?<currentValue>v[.\\d]+)[\"']?\\s*\\n\\s*sha256: [\"']?(?<currentDigest>\\w+)[\"']?"],
+      matchStrings: ["jdx/mise-action.*\\n\\s*with:\\s*\\n\\s*version: [\"']?(?<currentValue>v[.\\d]+)[\"']?\\s*\\n\\s*sha256:\\s*(?:(?:[>|][-+]?)\\s*\\n\\s*)?[\"']?(?<currentDigest>[a-f0-9]{64})[\"']?"],
     },
     {
       customType: "regex",
@@ -90,7 +90,7 @@
       datasourceTemplate: "github-release-attachments",
       packageNameTemplate: "jdx/mise",
       depNameTemplate: "mise",
-      matchStrings: ["jdx/mise-action.*\\n\\s*with:\\s*\\n\\s*version: [\"']?(?<currentValue>v[.\\d]+)[\"']?\\s*\\n\\s*sha256: [\"']?(?<currentDigest>\\w+)[\"']?"],
+      matchStrings: ["jdx/mise-action.*\\n\\s*with:\\s*\\n\\s*version: [\"']?(?<currentValue>v[.\\d]+)[\"']?\\s*\\n\\s*sha256:\\s*(?:(?:[>|][-+]?)\\s*\\n\\s*)?[\"']?(?<currentDigest>[a-f0-9]{64})[\"']?"],
     },
   ],
   packageRules: [
diff --git a/default.json b/default.json
index 448b4523..02b31fca 100644
--- a/default.json
+++ b/default.json
@@ -30,7 +30,7 @@
       "packageNameTemplate": "jdx/mise",
       "depNameTemplate": "mise",
       "matchStrings": [
-        "jdx/mise-action.*\\n\\s*with:\\s*\\n\\s*version: [\"']?(?<currentValue>v[.\\d]+)[\"']?\\s*\\n\\s*sha256: [\"']?(?<currentDigest>\\w+)[\"']?"
+        "jdx/mise-action.*\\n\\s*with:\\s*\\n\\s*version: [\"']?(?<currentValue>v[.\\d]+)[\"']?\\s*\\n\\s*sha256:\\s*(?:(?:[>|][-+]?)\\s*\\n\\s*)?[\"']?(?<currentDigest>[a-f0-9]{64})[\"']?"
       ]
     }
   ],
diff --git a/src/registry/tests.rs b/src/registry/tests.rs
index 641408ae..b73b24a7 100644
--- a/src/registry/tests.rs
+++ b/src/registry/tests.rs
@@ -1,6 +1,8 @@
 use std::collections::{BTreeSet, HashMap};
 use std::path::Path;
 
+use regex::Regex;
+
 use super::*;
 
 #[path = "../readme_snippets.rs"]
@@ -509,6 +511,68 @@ fn repo_renovate_config_stays_aligned_with_shared_preset_contract() {
     }
 }
 
+#[test]
+fn mise_action_custom_manager_matches_plain_and_block_scalar_sha256() {
+    let manifest_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
+    let default_json_path = manifest_dir.join("default.json");
+    let default_json =
+        std::fs::read_to_string(&default_json_path).expect("default.json must be readable");
+    let parsed: serde_json::Value =
+        serde_json::from_str(&default_json).expect("default.json must be valid JSON");
+
+    let description = "Update mise version in GitHub Actions workflows";
+    let manager = custom_manager_by_description(&parsed, description)
+        .unwrap_or_else(|| panic!("default.json missing custom manager {description:?}"));
+    let pattern = manager["matchStrings"][0]
+        .as_str()
+        .expect("custom manager match string must be a string");
+    let regex = Regex::new(pattern).expect("custom manager regex must compile");
+
+    for (name, sample) in [
+        (
+            "plain scalar",
+            r#"
+      - name: Setup mise
+        uses: jdx/mise-action@1648a7812b9aeae629881980618f079932869151 # v4.0.1
+        with:
+          version: v2026.4.28
+          sha256: 9655492db554e8f70a69830f54307ac0f4681d6c42f9844e862528b7853d09d1
+"#,
+        ),
+        (
+            "block scalar",
+            r#"
+      - name: Setup mise
+        uses: jdx/mise-action@1648a7812b9aeae629881980618f079932869151 # v4.0.1
+        with:
+          version: v2026.4.28
+          sha256: >-
+            c55befc52e5694f388b927ef304362ca7b9e919d97d43c342fca57f2eccea255
+"#,
+        ),
+    ] {
+        let captures = regex
+            .captures(sample)
+            .unwrap_or_else(|| panic!("regex must match {name} mise-action YAML"));
+        assert_eq!(
+            captures.name("currentValue").map(|value| value.as_str()),
+            Some("v2026.4.28"),
+            "regex must capture the mise version for {name}"
+        );
+        assert_eq!(
+            captures.name("currentDigest").map(|value| value.as_str()),
+            Some(match name {
+                "plain scalar" =>
+                    "9655492db554e8f70a69830f54307ac0f4681d6c42f9844e862528b7853d09d1",
+                "block scalar" =>
+                    "c55befc52e5694f388b927ef304362ca7b9e919d97d43c342fca57f2eccea255",
+                _ => unreachable!("unexpected sample"),
+            }),
+            "regex must capture the mise sha256 digest for {name}"
+        );
+    }
+}
+
 #[test]
 fn linter_keys_include_mise_and_bare_tool_names() {
     let keys = linter_keys();