diff --git a/src/asm/lexer.cpp b/src/asm/lexer.cpp
index 4e329ee6..050a206f 100644
--- a/src/asm/lexer.cpp
+++ b/src/asm/lexer.cpp
@@ -49,11 +49,31 @@ struct Token {
 	int type;
 	std::variant<std::monostate, uint32_t, std::string> value;
 
-	Token() : type(T_(NUMBER)), value(std::monostate{}) {}
-	Token(int type_) : type(type_), value(std::monostate{}) {}
-	Token(int type_, uint32_t value_) : type(type_), value(value_) {}
-	Token(int type_, std::string const &value_) : type(type_), value(std::move(value_)) {}
-	Token(int type_, std::string &&value_) : type(type_), value(std::move(value_)) {}
+	Token() : type(T_(NUMBER)), value(std::monostate{}) {
+		assume(
+		    type != T_(NUMBER) && type != T_(STRING) && type != T_(CHARACTER) && type != T_(SYMBOL)
+		    && type != T_(LABEL) && type != T_(LOCAL) && type != T_(ANON) && type != T_(QMACRO)
+		);
+	}
+	Token(int type_) : type(type_), value(std::monostate{}) {
+		assume(
+		    type != T_(NUMBER) && type != T_(STRING) && type != T_(CHARACTER) && type != T_(SYMBOL)
+		    && type != T_(LABEL) && type != T_(LOCAL) && type != T_(ANON) && type != T_(QMACRO)
+		);
+	}
+	Token(int type_, uint32_t value_) : type(type_), value(value_) { assume(type == T_(NUMBER)); }
+	Token(int type_, std::string const &value_) : type(type_), value(std::move(value_)) {
+		assume(
+		    type == T_(STRING) || type == T_(CHARACTER) || type == T_(SYMBOL) || type == T_(LABEL)
+		    || type == T_(LOCAL) || type == T_(ANON) || type == T_(QMACRO)
+		);
+	}
+	Token(int type_, std::string &&value_) : type(type_), value(std::move(value_)) {
+		assume(
+		    type == T_(STRING) || type == T_(CHARACTER) || type == T_(SYMBOL) || type == T_(LABEL)
+		    || type == T_(LOCAL) || type == T_(ANON) || type == T_(QMACRO)
+		);
+	}
 };
 
 // This map lists all RGBASM keywords which `yylex_NORMAL` lexes as identifiers.