diff --git a/package.json b/package.json
index a75a73b4f..70d52eb8a 100644
--- a/package.json
+++ b/package.json
@@ -32,7 +32,7 @@
     "ember-assign-polyfill": "^2.6.0"
   },
   "dependencies": {
-    "@glimmer/syntax": "^0.65.0",
+    "@glimmer/syntax": "^0.66.0",
     "broccoli-bridge": "^1.0.0",
     "broccoli-caching-writer": "^3.0.3",
     "broccoli-debug": "^0.6.5",
diff --git a/yarn.lock b/yarn.lock
index 957392d32..ed1cee0f7 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1358,10 +1358,10 @@
   dependencies:
     "@simple-dom/interface" "^1.4.0"
 
-"@glimmer/interfaces@0.65.0":
-  version "0.65.0"
-  resolved "https://registry.yarnpkg.com/@glimmer/interfaces/-/interfaces-0.65.0.tgz#e3852efb63fc9f18268991caea4ab362b75ae231"
-  integrity sha512-Ka9/w1u7SjWt8ZKa3Gs9IbFtLLDlaCdCTO7B+/Lat0bxGIctyEAyjxUdVqUwXWO4pMfkEFWKBP3L/t9CRT8sVQ==
+"@glimmer/interfaces@0.66.0":
+  version "0.66.0"
+  resolved "https://registry.yarnpkg.com/@glimmer/interfaces/-/interfaces-0.66.0.tgz#f281e1985d6b7f63648d960cc2745c68562fdb92"
+  integrity sha512-fw1pO6oyczSKeTPR6anrSI4OarLlaAR0SSDAhsYrINXfW7Xd/U/es7i6VE1JjLSZqfnsAxjNOFDe0lA5lmV/dw==
   dependencies:
     "@simple-dom/interface" "^1.4.0"
 
@@ -1424,13 +1424,13 @@
     "@handlebars/parser" "^1.1.0"
     simple-html-tokenizer "^0.5.10"
 
-"@glimmer/syntax@^0.65.0":
-  version "0.65.0"
-  resolved "https://registry.yarnpkg.com/@glimmer/syntax/-/syntax-0.65.0.tgz#a4fd943ca558e15c77619d49a4d4500dd252868c"
-  integrity sha512-juVFrA62oFdr2FSxLMb7c3j7KU/onQlC7c4E9rnkivXqE7EmNGI7/+I48L/DsMmDOZDOf4bIhjeCWbXNB4dS9g==
+"@glimmer/syntax@^0.66.0":
+  version "0.66.0"
+  resolved "https://registry.yarnpkg.com/@glimmer/syntax/-/syntax-0.66.0.tgz#d38561be48f6c4deeb94c24a1344a3426bb7e925"
+  integrity sha512-sgGQvoLprHjGV/TW2WY5wTmJaUjkHHgXhRJp+nLL5+JVC1zoR/mbGJk2Wfbj/R5D3pKzPln08HsSdXKj9Dl36g==
   dependencies:
-    "@glimmer/interfaces" "0.65.0"
-    "@glimmer/util" "0.65.0"
+    "@glimmer/interfaces" "0.66.0"
+    "@glimmer/util" "0.66.0"
     "@handlebars/parser" "^1.1.0"
     simple-html-tokenizer "^0.5.10"
 
@@ -1451,13 +1451,13 @@
     "@glimmer/interfaces" "0.62.4"
     "@simple-dom/interface" "^1.4.0"
 
-"@glimmer/util@0.65.0":
-  version "0.65.0"
-  resolved "https://registry.yarnpkg.com/@glimmer/util/-/util-0.65.0.tgz#8a90382500334e415415bf51b269bc7484b17543"
-  integrity sha512-tfsKVJpCJ5ADWXgpouiitIKlNacWQseYAlppgn8Y6LnzxcywgnumwFObkfzYlFE6Nd1IiymNxgEeSNJKylWl1A==
+"@glimmer/util@0.66.0":
+  version "0.66.0"
+  resolved "https://registry.yarnpkg.com/@glimmer/util/-/util-0.66.0.tgz#c457951951f4ea1d5a1d63fa11c9ffeae8efa4f6"
+  integrity sha512-4J3sihRKZ7N4igk2BZGryC/E6qIy+20d3Dl9+jYhsM8SdviPm+PtFy7tdJsb3E+u/yITqHnvzt7+Cr+VtlT7KA==
   dependencies:
     "@glimmer/env" "0.1.7"
-    "@glimmer/interfaces" "0.65.0"
+    "@glimmer/interfaces" "0.66.0"
     "@simple-dom/interface" "^1.4.0"
 
 "@glimmer/util@^0.42.2":