diff --git a/lib/binary_parser.ts b/lib/binary_parser.ts
index cf511f6..ff24295 100644
--- a/lib/binary_parser.ts
+++ b/lib/binary_parser.ts
@@ -644,6 +644,12 @@ export class Parser {
       throw new Error("length or readUntil must be defined for wrapped.");
     }
 
+    if (!(options.type instanceof Parser) && !varName) {
+      throw new Error(
+        "type must be a Parser object if the variable name is omitted.",
+      );
+    }
+
     return this.setNextParser("wrapper", varName as string, options);
   }
 
@@ -702,6 +708,18 @@ export class Parser {
       ) {
         throw new Error(`Choice type "${value}" is unknown.`);
       }
+
+      if (typeof value === "string" && !varName) {
+        throw new Error(
+          "Choice type must be a Parser object if the variable name is omitted.",
+        );
+      }
+    }
+
+    if (typeof options.defaultChoice === "string" && !varName) {
+      throw new Error(
+        "defaultChoice must be a Parser object if the variable name is omitted.",
+      );
     }
 
     return this.setNextParser("choice", varName as string, options);
diff --git a/test/composite_parser.ts b/test/composite_parser.ts
index b369b54..40aa3b0 100644
--- a/test/composite_parser.ts
+++ b/test/composite_parser.ts
@@ -877,6 +877,27 @@ function compositeParserTests(
           },
         });
       });
+      it("should throw if varName is omitted and a choice is a string", () => {
+        Parser.start().uint8("v").namely("choiceNoVarNameAlias");
+        expect(() =>
+          new Parser().uint8("tag").choice({
+            tag: "tag",
+            choices: { 1: "choiceNoVarNameAlias" },
+          }),
+        ).toThrow();
+        expect(() =>
+          new Parser()
+            .uint8("tag")
+            .choice({ tag: "tag", choices: { 1: "uint8" } }),
+        ).toThrow();
+        expect(() =>
+          new Parser().uint8("tag").choice({
+            tag: "tag",
+            choices: { 1: Parser.start().uint8("v") },
+            defaultChoice: "uint8",
+          }),
+        ).toThrow();
+      });
     });
 
     describe("Nest parser", () => {
@@ -1452,6 +1473,16 @@ function compositeParserTests(
           parserWithoutName.parse(buffer),
         );
       });
+      it("should throw if varName is omitted and type is a string", () => {
+        Parser.start().uint8("v").namely("wrappedNoVarNameAlias");
+        expect(() =>
+          new Parser().uint8("x").wrapped({
+            length: 1,
+            wrapper: (b: Uint8Array) => b,
+            type: "wrappedNoVarNameAlias",
+          }),
+        ).toThrow();
+      });
     });
   });
 }