diff --git a/hphp/hack/src/parser/lowerer/desugar_expression_tree.rs b/hphp/hack/src/parser/lowerer/desugar_expression_tree.rs
index 669a1063bdc8a3..7665c8da9e9fc1 100644
--- a/hphp/hack/src/parser/lowerer/desugar_expression_tree.rs
+++ b/hphp/hack/src/parser/lowerer/desugar_expression_tree.rs
@@ -1609,6 +1609,11 @@ impl RewriteState {
                 ));
                 unchanged_result
             }
+            Yield(_) => {
+                self.errors
+                    .push((pos, "`yield` is not supported in expression trees.".into()));
+                unchanged_result
+            }
             _ => {
                 self.errors
                     .push((pos, "Unsupported expression tree syntax.".into()));
diff --git a/hphp/hack/src/parser/lowerer/lowerer.rs b/hphp/hack/src/parser/lowerer/lowerer.rs
index e4fdbfc79e8bba..1a69b422a8377c 100644
--- a/hphp/hack/src/parser/lowerer/lowerer.rs
+++ b/hphp/hack/src/parser/lowerer/lowerer.rs
@@ -187,7 +187,7 @@ pub struct Env<'a> {
     pub empty_ns_env: Arc<NamespaceEnv>,
 
     // Whether we have encountered an yield expression
-    pub found_yield: bool,
+    found_yield: bool,
     // Whether we have encountered an await expression
     found_await: bool,
     // Whether we are in the body of an async function
@@ -2377,8 +2377,7 @@ fn p_prefixed_code_expr<'a>(
         let pos = p_pos(&c.body, env);
         let suspension_kind = SuspensionKind::SKSync;
         // Take the body and create a no argument lambda expression
-        let (body, yield_) =
-            env.reset_for_function_body(&c.body, suspension_kind, p_function_body)?;
+        let body = p_function_body(&c.body, env)?;
         let external = c.body.is_external();
         let fun = ast::Fun_ {
             span: pos.clone(),
@@ -2387,7 +2386,7 @@ fn p_prefixed_code_expr<'a>(
             readonly_ret: None,
             ret: ast::TypeHint((), None),
             body: ast::FuncBody { fb_ast: body },
-            fun_kind: mk_fun_kind(suspension_kind, yield_),
+            fun_kind: mk_fun_kind(suspension_kind, false),
             params: vec![],
             ctxs: None,
             unsafe_ctxs: None,
diff --git a/hphp/hack/test/typecheck/expression_trees/async_generator.php.exp b/hphp/hack/test/typecheck/expression_trees/async_generator.php.exp
index 7018920d92dbdf..1edc5b11ce62fb 100644
--- a/hphp/hack/test/typecheck/expression_trees/async_generator.php.exp
+++ b/hphp/hack/test/typecheck/expression_trees/async_generator.php.exp
@@ -3,7 +3,7 @@ Internal error: Return type is not a generator (Other[0000])
 ERROR: File "async_generator.php", line 6, characters 14-38:
 Expression trees only support simple lambdas, without features like `async`, generators or capabilities. (Parsing[1002])
 ERROR: File "async_generator.php", line 6, characters 29-35:
-Unsupported expression tree syntax. (Parsing[1002])
+`yield` is not supported in expression trees. (Parsing[1002])
 ERROR: File "async_generator.php", line 6, characters 14-38:
 You cannot return a value in a generator (a generator is a function that uses `yield`) (NastCheck[3019])
 ERROR: File "async_generator.php", line 6, characters 14-38:
diff --git a/hphp/hack/test/typecheck/expression_trees/generator.php.exp b/hphp/hack/test/typecheck/expression_trees/generator.php.exp
index f56342aa6599b3..7b5be27c9b7fce 100644
--- a/hphp/hack/test/typecheck/expression_trees/generator.php.exp
+++ b/hphp/hack/test/typecheck/expression_trees/generator.php.exp
@@ -3,7 +3,7 @@ Internal error: Return type is not a generator (Other[0000])
 ERROR: File "generator.php", line 6, characters 14-32:
 Expression trees only support simple lambdas, without features like `async`, generators or capabilities. (Parsing[1002])
 ERROR: File "generator.php", line 6, characters 23-29:
-Unsupported expression tree syntax. (Parsing[1002])
+`yield` is not supported in expression trees. (Parsing[1002])
 ERROR: File "generator.php", line 6, characters 14-32:
 You cannot return a value in a generator (a generator is a function that uses `yield`) (NastCheck[3019])
 ERROR: File "generator.php", line 6, characters 14-32:
diff --git a/hphp/hack/test/typecheck/expression_trees/nesting/await.php b/hphp/hack/test/typecheck/expression_trees/nesting/await.php
new file mode 100644
index 00000000000000..b7cd81d79d3e78
--- /dev/null
+++ b/hphp/hack/test/typecheck/expression_trees/nesting/await.php
@@ -0,0 +1,33 @@
+<?hh
+<<file: __EnableUnstableFeatures('expression_trees')>>
+
+async function g(): Awaitable<ExampleDslExpression<ExampleInt>> {
+  return ExampleDsl`1`;
+}
+
+async function f(): Awaitable<void> {
+  ExampleDsl`${ExampleDsl`${await g()}`}`;
+  ExampleDsl`{
+    ${await g()};
+  }`;
+  ExampleDsl`${
+    ExampleDsl`{
+      1;
+      ${await g()};
+    }`
+  }`;
+  ExampleDsl`{
+    ${ExampleDsl`${await g()}`};
+  }`;
+  ExampleDsl`{
+    ${await g()};
+    ${ExampleDsl`${await g()}`};
+  }`;
+  ExampleDsl`{
+    ${
+      ExampleDsl`{
+        ${await g()};
+      }`
+    };
+  }`;
+}
diff --git a/hphp/hack/test/typecheck/expression_trees/nesting/await.php.exp b/hphp/hack/test/typecheck/expression_trees/nesting/await.php.exp
new file mode 100644
index 00000000000000..4269126fcebc19
--- /dev/null
+++ b/hphp/hack/test/typecheck/expression_trees/nesting/await.php.exp
@@ -0,0 +1 @@
+No errors
diff --git a/hphp/test/slow/expression_trees/blocks_yield.php.expectf b/hphp/test/slow/expression_trees/blocks_yield.php.expectf
index 80cc13569fa5e2..89dd3bd729a860 100644
--- a/hphp/test/slow/expression_trees/blocks_yield.php.expectf
+++ b/hphp/test/slow/expression_trees/blocks_yield.php.expectf
@@ -1 +1 @@
-Fatal error: Expression trees only support simple lambdas, without features like `async`, generators or capabilities. in %s/blocks_yield.php on line 14
+Fatal error: `yield` is not supported in expression trees. in %s/blocks_yield.php on line 12