diff --git a/lib/coffeescript/lexer.js b/lib/coffeescript/lexer.js
index c067570dea..d933f71791 100644
--- a/lib/coffeescript/lexer.js
+++ b/lib/coffeescript/lexer.js
@@ -10,7 +10,7 @@
   // where locationData is {first_line, first_column, last_line, last_column, last_line_exclusive, last_column_exclusive}, which is a
   // format that can be fed directly into [Jison](https://github.com/zaach/jison).  These
   // are read by jison in the `parser.lexer` function defined in coffeescript.coffee.
-  var BOM, BOOL, CALLABLE, CODE, COFFEE_ALIASES, COFFEE_ALIAS_MAP, COFFEE_KEYWORDS, COMMENT, COMPARABLE_LEFT_SIDE, COMPARE, COMPOUND_ASSIGN, HERECOMMENT_ILLEGAL, HEREDOC_DOUBLE, HEREDOC_INDENT, HEREDOC_SINGLE, HEREGEX, HEREGEX_COMMENT, HERE_JSTOKEN, IDENTIFIER, INDENTABLE_CLOSERS, INDEXABLE, INSIDE_JSX, INVERSES, JSTOKEN, JSX_ATTRIBUTE, JSX_FRAGMENT_IDENTIFIER, JSX_IDENTIFIER, JSX_IDENTIFIER_PART, JSX_INTERPOLATION, JS_KEYWORDS, LINE_BREAK, LINE_CONTINUER, Lexer, MATH, MULTI_DENT, NOT_REGEX, NUMBER, OPERATOR, POSSIBLY_DIVISION, REGEX, REGEX_FLAGS, REGEX_ILLEGAL, REGEX_INVALID_ESCAPE, RELATION, RESERVED, Rewriter, SHIFT, STRICT_PROSCRIBED, STRING_DOUBLE, STRING_INVALID_ESCAPE, STRING_SINGLE, STRING_START, TRAILING_SPACES, UNARY, UNARY_MATH, UNFINISHED, VALID_FLAGS, WHITESPACE, addTokenData, attachCommentsToNode, compact, count, flatten, invertLiterate, isForFrom, isUnassignable, key, locationDataToString, merge, parseNumber, repeat, replaceUnicodeCodePointEscapes, starts, throwSyntaxError,
+  var BOM, BOOL, CALLABLE, CODE, COFFEE_ALIASES, COFFEE_ALIAS_MAP, COFFEE_KEYWORDS, COMMENT, COMPARABLE_LEFT_SIDE, COMPARE, COMPOUND_ASSIGN, DISTINCT_DECL, HERECOMMENT_ILLEGAL, HEREDOC_DOUBLE, HEREDOC_INDENT, HEREDOC_SINGLE, HEREGEX, HEREGEX_COMMENT, HERE_JSTOKEN, IDENTIFIER, INDENTABLE_CLOSERS, INDEXABLE, INSIDE_JSX, INVERSES, JSTOKEN, JSX_ATTRIBUTE, JSX_FRAGMENT_IDENTIFIER, JSX_IDENTIFIER, JSX_IDENTIFIER_PART, JSX_INTERPOLATION, JS_KEYWORDS, LINE_BREAK, LINE_CONTINUER, Lexer, MATH, MULTI_DENT, NOT_REGEX, NUMBER, OPERATOR, POSSIBLY_DIVISION, REGEX, REGEX_FLAGS, REGEX_ILLEGAL, REGEX_INVALID_ESCAPE, RELATION, RESERVED, Rewriter, SHIFT, STRICT_PROSCRIBED, STRING_DOUBLE, STRING_INVALID_ESCAPE, STRING_SINGLE, STRING_START, TRAILING_SPACES, UNARY, UNARY_MATH, UNFINISHED, VALID_FLAGS, WHITESPACE, addTokenData, attachCommentsToNode, compact, count, flatten, invertLiterate, isForFrom, isUnassignable, key, locationDataToString, merge, parseNumber, repeat, replaceUnicodeCodePointEscapes, starts, throwSyntaxError,
     indexOf = [].indexOf,
     slice = [].slice;
 
@@ -1109,6 +1109,8 @@
         if (CODE.test(value)) {
           this.tagParameters();
         }
+      } else if (match = DISTINCT_DECL.exec(this.chunk)) {
+        [value] = match;
       } else {
         value = this.chunk.charAt(0);
       }
@@ -1139,6 +1141,9 @@
           return value.length;
         }
       }
+      if (value === '@=') {
+        tag = 'DECLARATION';
+      }
       if (value === '(' && (prev != null ? prev[0] : void 0) === 'IMPORT') {
         prev[0] = 'DYNAMIC_IMPORT';
       }
@@ -1945,4 +1950,8 @@
   // Additional indent in front of these is ignored.
   INDENTABLE_CLOSERS = [')', '}', ']'];
 
+  // Proposed syntax for "declarations", which are checked to be unique in a scope and can therefore
+  // have additional semantic information attached which would otherwise be erased.
+  DISTINCT_DECL = /^(?:@=)/; // distinct var decl which can have a specific comment attached.
+
 }).call(this);
diff --git a/src/lexer.coffee b/src/lexer.coffee
index d2a3cd35da..51195b59c9 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -756,6 +756,8 @@ exports.Lexer = class Lexer
     if match = OPERATOR.exec @chunk
       [value] = match
       @tagParameters() if CODE.test value
+    else if match = DISTINCT_DECL.exec @chunk
+      [value] = match
     else
       value = @chunk.charAt 0
     tag  = value
@@ -781,6 +783,9 @@ exports.Lexer = class Lexer
         @error message, origin[2] if message
       return value.length if skipToken
 
+    if value is '@='
+      tag = 'DECLARATION'
+
     if value is '(' and prev?[0] is 'IMPORT'
       prev[0] = 'DYNAMIC_IMPORT'
 
@@ -1479,3 +1484,9 @@ LINE_BREAK = ['INDENT', 'OUTDENT', 'TERMINATOR']
 
 # Additional indent in front of these is ignored.
 INDENTABLE_CLOSERS = [')', '}', ']']
+
+# Proposed syntax for "declarations", which are checked to be unique in a scope and can therefore
+# have additional semantic information attached which would otherwise be erased.
+DISTINCT_DECL = /// ^ (
+  ?: @=                # distinct var decl which can have a specific comment attached.
+) ///