diff --git a/lib/core.ts b/lib/core.ts
index d0085608b..f469d5d82 100644
--- a/lib/core.ts
+++ b/lib/core.ts
@@ -742,7 +742,7 @@ function getLogger(logger?: Partial<Logger> | false): Logger {
   throw new Error("logger must implement log, warn and error methods")
 }
 
-const KEYWORD_NAME = /^[a-z_$][a-z0-9_$-:]*$/i
+const KEYWORD_NAME = /^[a-z_$][a-z0-9_$:-]*$/i
 
 function checkKeyword(this: Ajv, keyword: string | string[], def?: KeywordDefinition): void {
   const {RULES} = this
diff --git a/spec/keyword.spec.ts b/spec/keyword.spec.ts
index 3508c2361..d27831b39 100644
--- a/spec/keyword.spec.ts
+++ b/spec/keyword.spec.ts
@@ -1099,6 +1099,10 @@ describe("User-defined keywords", () => {
         ajv.addKeyword("colons:are-valid")
       })
 
+      should.throw(() => {
+        ajv.addKeyword("single-'quote-not-valid")
+      }, /invalid name/)
+
       should.throw(() => {
         ajv.addKeyword("3-start-with-number-not-valid")
       }, /invalid name/)