diff --git a/src/Stmt.cc b/src/Stmt.cc
index cf455c44ed..6041e16e8a 100644
--- a/src/Stmt.cc
+++ b/src/Stmt.cc
@@ -52,6 +52,7 @@ const char* stmt_name(StmtTag t) {
         "ZAM",
         "null",
         "assert",
+        "extern",
     };
 
     return stmt_names[int(t)];
diff --git a/src/StmtEnums.h b/src/StmtEnums.h
index 3eb463eab9..7a237cb043 100644
--- a/src/StmtEnums.h
+++ b/src/StmtEnums.h
@@ -31,7 +31,8 @@ enum StmtTag {
     STMT_ZAM,           // a ZAM function body
     STMT_NULL,
     STMT_ASSERT,
-#define NUM_STMTS (int(STMT_ASSERT) + 1)
+    STMT_EXTERN, // for custom Stmt subclasses provided by plugins
+#define NUM_STMTS (int(STMT_EXTERN) + 1)
 };
 
 enum StmtFlowType {