diff --git a/parser/argument.go b/parser/argument.go
new file mode 100644
index 0000000..6a94bee
--- /dev/null
+++ b/parser/argument.go
@@ -0,0 +1,76 @@
+package parser
+
+import "git.tebibyte.media/sashakoshka/arf/file"
+import "git.tebibyte.media/sashakoshka/arf/lexer"
+
+var validArgumentStartTokens = []lexer.TokenKind {
+	lexer.TokenKindName,
+	
+	lexer.TokenKindInt,
+	lexer.TokenKindUInt,
+	lexer.TokenKindFloat,
+	lexer.TokenKindString,
+	lexer.TokenKindRune,
+	
+	lexer.TokenKindLBrace,
+	lexer.TokenKindLBracket,
+}
+
+func (parser *ParsingOperation) parseArgument () (argument Argument, err error) {
+	argument.location = parser.token.Location()
+
+	err = parser.expect(validArgumentStartTokens...)
+	if err != nil { return }
+
+	switch parser.token.Kind() {
+	case lexer.TokenKindName:
+		var identifier Identifier
+		identifier, err = parser.parseIdentifier()
+		if err != nil { return }
+
+		if parser.token.Is(lexer.TokenKindColon) {
+			var what Type
+			what, err = parser.parseType()
+			if err != nil { return }
+
+			if len(identifier.trail) != 1 {
+				err = parser.token.NewError (
+					"cannot use member selection in " +
+					"a variable definition",
+					file.ErrorKindError)
+				return
+			}
+
+			argument.kind  = ArgumentKindDeclaration
+			argument.value = Declaration {
+				location: argument.location,
+				name:     identifier.trail[0],
+				what:     what,
+			}
+		} else {
+			argument.kind  = ArgumentKindIdentifier
+			argument.value = identifier
+		}
+		
+	case lexer.TokenKindInt:
+		
+	case lexer.TokenKindUInt:
+		
+	case lexer.TokenKindFloat:
+		
+	case lexer.TokenKindString:
+		
+	case lexer.TokenKindRune:
+		
+	case lexer.TokenKindLBrace:
+		
+	case lexer.TokenKindLBracket:
+
+	default:
+		panic (
+			"unimplemented argument kind " +
+			parser.token.Kind().Describe())
+	}
+
+	return
+}