diff --git a/packages/@opticss/demo-app/package.json b/packages/@opticss/demo-app/package.json
index a1144700..8d2e6bbe 100644
--- a/packages/@opticss/demo-app/package.json
+++ b/packages/@opticss/demo-app/package.json
@@ -44,7 +44,7 @@
     "codemirror": "^5.15.2",
     "express": "^4.15.5",
     "opticss": "^0.7.0",
-    "parse5": "^5.0.0",
+    "parse5": "^6.0.0",
     "prettier": "1.17.1",
     "split.js": "^1.3.5"
   },
diff --git a/packages/@opticss/simple-template/package.json b/packages/@opticss/simple-template/package.json
index 1fb85097..c269f3ec 100644
--- a/packages/@opticss/simple-template/package.json
+++ b/packages/@opticss/simple-template/package.json
@@ -43,7 +43,7 @@
     "@opticss/template-api": "^0.6.3",
     "@opticss/util": "^0.7.0",
     "@types/random-js": "^1.0.30",
-    "parse5": "^5.0.0",
+    "parse5": "^6.0.0",
     "parse5-sax-parser": "^5.0.0",
     "postcss": "^7.0.14",
     "random-js": "^2.0.0",
diff --git a/packages/resolve-cascade/package.json b/packages/resolve-cascade/package.json
index 72e6d961..70c2401f 100644
--- a/packages/resolve-cascade/package.json
+++ b/packages/resolve-cascade/package.json
@@ -60,7 +60,7 @@
     "css-property-parser": "^1.0.5",
     "css-size": "^4.0.1",
     "domutils": "^1.6.2",
-    "parse5": "^5.0.0",
+    "parse5": "^6.0.0",
     "postcss": "^7.0.14",
     "specificity": "^0.4.1"
   },
diff --git a/yarn.lock b/yarn.lock
index c772a8fb..a85a5cbc 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6925,11 +6925,16 @@ parse5@4.0.0:
   resolved "https://registry.yarnpkg.com/parse5/-/parse5-4.0.0.tgz#6d78656e3da8d78b4ec0b906f7c08ef1dfe3f608"
   integrity sha512-VrZ7eOd3T1Fk4XWNXMgiGBK/z0MG48BWG2uQNU4I72fkQuKUTZpl+u9k+CxEG0twMVzSmXEEz12z5Fnw1jIQFA==
 
-parse5@^5.0.0, parse5@^5.1.0:
+parse5@^5.1.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/parse5/-/parse5-5.1.0.tgz#c59341c9723f414c452975564c7c00a68d58acd2"
   integrity sha512-fxNG2sQjHvlVAYmzBZS9YlDp6PTSSDwa98vkD4QgVDDCAo84z5X1t5XyJQ62ImdLXx5NdIIfihey6xpum9/gRQ==
 
+parse5@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/parse5/-/parse5-6.0.0.tgz#d2ac3448289c84b49947d49a39f7bef6200fa6ba"
+  integrity sha512-lC0A+4DefTdRr+DLQlEwwZqndL9VzEjiuegI5bj3hp4bnzzwQldSqCpHv7+msRpSOHGJyJvkcCa4q15LMUJ8rg==
+
 parseurl@~1.3.3:
   version "1.3.3"
   resolved "https://registry.yarnpkg.com/parseurl/-/parseurl-1.3.3.tgz#9da19e7bee8d12dff0513ed5b76957793bc2e8d4"
@@ -7407,10 +7412,10 @@ preserve@^0.2.0:
   resolved "https://registry.yarnpkg.com/preserve/-/preserve-0.2.0.tgz#815ed1f6ebc65926f865b310c0713bcb3315ce4b"
   integrity sha1-gV7R9uvGWSb4ZbMQwHE7yzMVzks=
 
-prettier@1.17.0:
-  version "1.17.0"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.17.0.tgz#53b303676eed22cc14a9f0cec09b477b3026c008"
-  integrity sha512-sXe5lSt2WQlCbydGETgfm1YBShgOX4HxQkFPvbxkcwgDvGDeqVau8h+12+lmSVlP3rHPz0oavfddSZg/q+Szjw==
+prettier@1.17.1:
+  version "1.17.1"
+  resolved "https://registry.yarnpkg.com/prettier/-/prettier-1.17.1.tgz#ed64b4e93e370cb8a25b9ef7fef3e4fd1c0995db"
+  integrity sha512-TzGRNvuUSmPgwivDqkZ9tM/qTGW9hqDKWOE9YHiyQdixlKbv7kvEqsmDPrcHJTKwthU774TQwZXVtaQ/mMsvjg==
 
 pretty-bytes@^5.0.0:
   version "5.3.0"