diff --git a/example.js b/example.js
index 2e2955f..0d830f7 100644
--- a/example.js
+++ b/example.js
@@ -1,6 +1,6 @@
 "use strict";
 
-const { validateValue } = require("@validatem/core"); /* FIXME: Add to devDependencies */
+const { validateValue } = require("@validatem/core");
 const isNumber = require("./");
 
 console.log(validateValue(42, [ isNumber ])); // 42
diff --git a/package.json b/package.json
index 7bbc44f..e88830e 100644
--- a/package.json
+++ b/package.json
@@ -13,5 +13,8 @@
   "dependencies": {
     "@validatem/error": "^1.0.0",
     "is-number-object": "^1.0.4"
+  },
+  "devDependencies": {
+    "@validatem/core": "^0.3.1"
   }
 }
diff --git a/yarn.lock b/yarn.lock
index c933cd8..7eb3dd0 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2,6 +2,51 @@
 # yarn lockfile v1
 
 
+"@validatem/annotate-errors@^0.1.2":
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/@validatem/annotate-errors/-/annotate-errors-0.1.2.tgz#fa9152bb30f4f42b69496b527e38f0c31ff605a9"
+  integrity sha512-EuX7pzdYI/YpTmZcgdPG481Oi3elAg8JWh/LYXuE1h6MaZk3A8eP5DD33/l7EoKzrysn6y8nCsqNa1ngei562w==
+  dependencies:
+    "@validatem/match-validation-error" "^0.1.0"
+
+"@validatem/any-property@^0.1.0":
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/@validatem/any-property/-/any-property-0.1.1.tgz#808db7a4d85b26910f263307a6cdb5d2c0816282"
+  integrity sha512-2xJeuAYyx8po9liVTRbC6J/SQHeXqw9dGrqlFUcQXYtiMIUl34y5yJuhGZKQRZP+SoNc7+x4CuZ/npPULonJiA==
+  dependencies:
+    "@validatem/annotate-errors" "^0.1.2"
+    "@validatem/combinator" "^0.1.0"
+    "@validatem/error" "^1.0.0"
+    "@validatem/validation-result" "^0.1.1"
+    "@validatem/virtual-property" "^0.1.0"
+    default-value "^1.0.0"
+
+"@validatem/combinator@^0.1.0":
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/@validatem/combinator/-/combinator-0.1.1.tgz#202f31243f8d57cf87f1b449405b134e2fa40c5a"
+  integrity sha512-crzAYCmKUcb1DC5sSpdof4gWHX81VRmm+REWflhFuRlKH6JHRV5RcBCxEjlDfRrxW2yF6s9i0rQAOyVVE+GGAg==
+
+"@validatem/core@^0.3.1":
+  version "0.3.1"
+  resolved "https://registry.yarnpkg.com/@validatem/core/-/core-0.3.1.tgz#33ea24ba4d4c516b5836703aea7e7da0afb6c227"
+  integrity sha512-k9OgvVqxX6rKmnkEQGi14pBqsilXu8pIVelaQsI/3tI5xVDDE5podpuPAJVrIsepy2berCtN9KSD/NCDhX1wLg==
+  dependencies:
+    "@validatem/annotate-errors" "^0.1.2"
+    "@validatem/any-property" "^0.1.0"
+    "@validatem/error" "^1.0.0"
+    "@validatem/is-plain-object" "^0.1.0"
+    "@validatem/match-validation-error" "^0.1.0"
+    "@validatem/match-versioned-special" "^0.1.0"
+    "@validatem/match-virtual-property" "^0.1.0"
+    "@validatem/normalize-rules" "^0.1.0"
+    "@validatem/required" "^0.1.0"
+    "@validatem/validation-result" "^0.1.1"
+    assure-array "^1.0.0"
+    create-error "^0.3.1"
+    default-value "^1.0.0"
+    flatten "^1.0.3"
+    is-arguments "^1.0.4"
+
 "@validatem/error@^1.0.0":
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/@validatem/error/-/error-1.0.0.tgz#a975904aa4c3e7618d89088a393567a5e1778340"
@@ -9,12 +54,122 @@
   dependencies:
     create-error "^0.3.1"
 
+"@validatem/has-shape@^0.1.0":
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/@validatem/has-shape/-/has-shape-0.1.2.tgz#5ea8a6e07ce45d2ab12732128f39be8de37fe23e"
+  integrity sha512-yy6Pku/4LHKRdzRuH3qDXniMfatLdu9hhANDS/tHibWfejBXZwu5kyY3Zx3qgs2NroFUrVhPyz8ZmiJqd0oyAQ==
+  dependencies:
+    "@validatem/annotate-errors" "^0.1.2"
+    "@validatem/combinator" "^0.1.0"
+    "@validatem/error" "^1.0.0"
+    "@validatem/validation-result" "^0.1.1"
+    as-expression "^1.0.0"
+    default-value "^1.0.0"
+    flatten "^1.0.3"
+
+"@validatem/is-plain-object@^0.1.0":
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/@validatem/is-plain-object/-/is-plain-object-0.1.1.tgz#b7a3ef8ef960882c7c41e84ed709fa0bfb932e93"
+  integrity sha512-aNGbNIbKRpYI0lRBczlTBbiA+nqN52ADAASdySKg2/QeSCVtYS4uOIeCNIJRAgXe/5sUnLTuL4pgq628uAl7Kw==
+  dependencies:
+    "@validatem/error" "^1.0.0"
+    is-plain-obj "^2.1.0"
+
+"@validatem/match-special@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/match-special/-/match-special-0.1.0.tgz#4e0c28f1aee5bf53c1ef30bbf8c755d4946ae0ff"
+  integrity sha512-TFiq9Wk/1Hoja4PK85WwNYnwBXk3+Lgoj59ZIMxm2an1qmNYp8j+BnSvkKBflba451yIn6V1laU9NJf+/NYZgw==
+
+"@validatem/match-validation-error@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/match-validation-error/-/match-validation-error-0.1.0.tgz#fa87f5f1836e7c1d9bf6b75b2addf0a5b21e4c1e"
+  integrity sha512-6akGTk7DdulOreyqDiGdikwRSixQz/AlvARSX18dcWaTFc79KxCLouL2hyoFcor9IIUhu5RTY4/i756y4T1yxA==
+  dependencies:
+    "@validatem/match-versioned-special" "^0.1.0"
+
+"@validatem/match-versioned-special@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/match-versioned-special/-/match-versioned-special-0.1.0.tgz#2eacc48debecdbbe7e3d02f0c0a665afaea9bedf"
+  integrity sha512-xoOTY0bdA2ELj+ntcDVJ8YyMEFIJpjZ4HNPL9lGcbnRFwJBhQcHUAhUpZwkMxu02zH9wkNM1FvYGHxPz40745Q==
+
+"@validatem/match-virtual-property@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/match-virtual-property/-/match-virtual-property-0.1.0.tgz#4de2de1075987b5f3b356d3f2bcf6c0be5b5fb83"
+  integrity sha512-ssd3coFgwbLuqvZftLZTy3eHN0TFST8oTS2XTViQdXJPXVoJmwEKBpFhXgwnb5Ly1CE037R/KWpjhd1TP/56kQ==
+
+"@validatem/normalize-rules@^0.1.0":
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/@validatem/normalize-rules/-/normalize-rules-0.1.2.tgz#6529f17a6f36c6e2ae3ef285c59347c2ea208aa1"
+  integrity sha512-IHc81Sy/W0OiCbmvE3kTB+5OPVJnXWHP2tTXvKO6hVH0qykclMvIPRGgZf1s4dLaeOLKdkkfKyO/pLTVyNCIbA==
+  dependencies:
+    "@validatem/has-shape" "^0.1.0"
+    "@validatem/is-plain-object" "^0.1.0"
+    "@validatem/match-special" "^0.1.0"
+    assure-array "^1.0.0"
+    default-value "^1.0.0"
+    flatten "^1.0.3"
+    is-plain-obj "^2.1.0"
+
+"@validatem/required@^0.1.0":
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/@validatem/required/-/required-0.1.1.tgz#64f4a87333fc5955511634036b7f8948ed269170"
+  integrity sha512-vI4NzLfay4RFAzp7xyU34PHb8sAo6w/3frrNh1EY9Xjnw2zxjY5oaxwmbFP1jVevBE6QQEnKogtzUHz/Zuvh6g==
+
+"@validatem/validation-result@^0.1.1":
+  version "0.1.2"
+  resolved "https://registry.yarnpkg.com/@validatem/validation-result/-/validation-result-0.1.2.tgz#4e75cfd87305fc78f8d05ac84921a2c99a0348e0"
+  integrity sha512-okmP8JarIwIgfpaVcvZGuQ1yOsLKT3Egt49Ynz6h1MAeGsP/bGHXkkXtbiWOVsk5Tzku5vDVFSrFnF+5IEHKxw==
+  dependencies:
+    default-value "^1.0.0"
+
+"@validatem/virtual-property@^0.1.0":
+  version "0.1.0"
+  resolved "https://registry.yarnpkg.com/@validatem/virtual-property/-/virtual-property-0.1.0.tgz#880540dfd149f98ecf1095d93912e34443381fe4"
+  integrity sha512-JUUvWtdqoSkOwlsl20oB3qFHYIL05a/TAfdY4AJcs55QeVTiX5iI1b8IoQW644sIWWooBuLv+XwoxjRsQFczlQ==
+
+as-expression@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/as-expression/-/as-expression-1.0.0.tgz#7bc620ca4cb2fe0ee90d86729bd6add33b8fd831"
+  integrity sha512-Iqh4GxNUfxbJdGn6b7/XMzc8m1Dz2ZHouBQ9DDTzyMRO3VPPIAXeoY/sucRxxxXKbUtzwzWZSN6jPR3zfpYHHA==
+
+assure-array@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/assure-array/-/assure-array-1.0.0.tgz#4f4ad16a87659d6200a4fb7103462033d216ec1f"
+  integrity sha1-T0rRaodlnWIApPtxA0YgM9IW7B8=
+
 create-error@^0.3.1:
   version "0.3.1"
   resolved "https://registry.yarnpkg.com/create-error/-/create-error-0.3.1.tgz#69810245a629e654432bf04377360003a5351a23"
   integrity sha1-aYECRaYp5lRDK/BDdzYAA6U1GiM=
 
+default-value@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/default-value/-/default-value-1.0.0.tgz#8c6f52a5a1193fe78fdc9f86eb71d16c9757c83a"
+  integrity sha1-jG9SpaEZP+eP3J+G63HRbJdXyDo=
+  dependencies:
+    es6-promise-try "0.0.1"
+
+es6-promise-try@0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/es6-promise-try/-/es6-promise-try-0.0.1.tgz#10f140dad27459cef949973e5d21a087f7274b20"
+  integrity sha1-EPFA2tJ0Wc75SZc+XSGgh/cnSyA=
+
+flatten@^1.0.3:
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/flatten/-/flatten-1.0.3.tgz#c1283ac9f27b368abc1e36d1ff7b04501a30356b"
+  integrity sha512-dVsPA/UwQ8+2uoFe5GHtiBMu48dWLTdsuEd7CKGlZlD78r1TTWBvDuFaFGKCo/ZfEr95Uk56vZoX86OsHkUeIg==
+
+is-arguments@^1.0.4:
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/is-arguments/-/is-arguments-1.0.4.tgz#3faf966c7cba0ff437fb31f6250082fcf0448cf3"
+  integrity sha512-xPh0Rmt8NE65sNzvyUmWgI1tz3mKq74lGA0mL8LYZcoIzKOzDh6HmrYm3d18k60nHerC8A9Km8kYu87zfSFnLA==
+
 is-number-object@^1.0.4:
   version "1.0.4"
   resolved "https://registry.yarnpkg.com/is-number-object/-/is-number-object-1.0.4.tgz#36ac95e741cf18b283fc1ddf5e83da798e3ec197"
   integrity sha512-zohwelOAur+5uXtk8O3GPQ1eAcu4ZX3UwxQhUlfFFMNpUd83gXgjbhJh6HmB6LUNV/ieOLQuDwJO3dWJosUeMw==
+
+is-plain-obj@^2.1.0:
+  version "2.1.0"
+  resolved "https://registry.yarnpkg.com/is-plain-obj/-/is-plain-obj-2.1.0.tgz#45e42e37fccf1f40da8e5f76ee21515840c09287"
+  integrity sha512-YWnfyRwxL/+SsrWYfOpUtz5b3YD+nyfkHvjbcanzk8zgyO4ASD67uVMRt8k5bM4lLMDnXfriRhOpemw+NfT1eA==