diff --git a/.changeset/witty-hotels-ring.md b/.changeset/witty-hotels-ring.md
new file mode 100644
index 000000000..ab43afd37
--- /dev/null
+++ b/.changeset/witty-hotels-ring.md
@@ -0,0 +1,5 @@
+---
+"mobx-undecorate": patch
+---
+
+mobx-undecorate don't crash when node's loc is null
diff --git a/packages/mobx-undecorate/src/undecorate.ts b/packages/mobx-undecorate/src/undecorate.ts
index 8a52e5a5d..ea56a20f6 100644
--- a/packages/mobx-undecorate/src/undecorate.ts
+++ b/packages/mobx-undecorate/src/undecorate.ts
@@ -402,15 +402,19 @@ export default function transform(
         if (process.env.NODE_ENV === "test") {
             return
         }
-        const line = lines[node.loc!.start.line - 1]
-        const shortline = line.replace(/^\s*/, "")
-        console.warn(
-            `[mobx:undecorate] ${msg} at (${fileInfo.path}:${node.loc!.start.line}:${
-                node.loc!.start.column
-            }):\n\t${shortline}\n\t${"^".padStart(
-                node.loc!.start.column + 1 - line.indexOf(shortline),
-                " "
-            )}\n`
-        )
+        if (node.loc) {
+            const line = lines[node.loc.start.line - 1]
+            const shortline = line.replace(/^\s*/, "")
+            console.warn(
+                `[mobx:undecorate] ${msg} at (${fileInfo.path}:${node.loc.start.line}:${
+                    node.loc.start.column
+                }):\n\t${shortline}\n\t${"^".padStart(
+                    node.loc.start.column + 1 - line.indexOf(shortline),
+                    " "
+                )}\n`
+            )
+        } else {
+            console.warn(`[mobx:undecorate] ${msg} at (${fileInfo.path})\n`)
+        }
     }
 }