diff --git a/src/Expr.cc b/src/Expr.cc
index 951fe0fe1b..e5608af449 100644
--- a/src/Expr.cc
+++ b/src/Expr.cc
@@ -82,18 +82,19 @@ const char* expr_name(ExprTag t) {
         "record_coerce",
         "table_coerce",
         "vector_coerce",
+        "to_any_coerce",
+        "from_any_coerce",
         "sizeof",
         "cast",
         "is",
         "[:]=",
         "inline()",
+        "vec+=",
         "[]=",
         "$=",
-        "vec+=",
-        "to_any_coerce",
-        "from_any_coerce",
         "from_any_vec_coerce",
         "any[]",
+        "ZAM-builtin()",
         "nop",
 
     };
diff --git a/src/Expr.h b/src/Expr.h
index d60891f130..5284c0732f 100644
--- a/src/Expr.h
+++ b/src/Expr.h
@@ -86,22 +86,24 @@ enum ExprTag : int {
     EXPR_RECORD_COERCE,
     EXPR_TABLE_COERCE,
     EXPR_VECTOR_COERCE,
+    EXPR_TO_ANY_COERCE,
+    EXPR_FROM_ANY_COERCE,
     EXPR_SIZE,
     EXPR_CAST,
     EXPR_IS,
     EXPR_INDEX_SLICE_ASSIGN,
-    EXPR_INLINE,
 
-    // The following types of expressions are only created for
-    // ASTs transformed to reduced form; they aren't germane for
-    // ASTs produced by parsing .zeek script files.
+    // The following types of expressions are only created for ASTs
+    // transformed to reduced form; they aren't germane for ASTs produced
+    // by parsing .zeek script files. See script_opt/Expr.h for the
+    // corresponding definitions.
+    EXPR_INLINE,
+    EXPR_APPEND_TO,
     EXPR_INDEX_ASSIGN,
     EXPR_FIELD_LHS_ASSIGN,
-    EXPR_APPEND_TO,
-    EXPR_TO_ANY_COERCE,
-    EXPR_FROM_ANY_COERCE,
     EXPR_FROM_ANY_VEC_COERCE,
     EXPR_ANY_INDEX,
+    EXPR_SCRIPT_OPT_BUILTIN,
 
     EXPR_NOP,