diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index 2746faa34e4879f1059b117dc7bd00e7c84d6240..7e801dde21652628324c22b28767caad82e09343 100644
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -339,7 +339,7 @@ $tab+         { warn Opt_WarnTabs (text "Tab character") }
 }
 
 <0> {
-  "(#" / { ifExtension unboxedTuplesEnabled `alexAndPred` notFollowedBySymbol }
+  "(#" / { ifExtension unboxedTuplesEnabled }
          { token IToubxparen }
   "#)" / { ifExtension unboxedTuplesEnabled }
          { token ITcubxparen }
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index c4dd6bbf5efd7da891f59cd9dab148a51833f14c..1357395eff1cd97002582e4fbb047209346e8b9a 100644
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -224,6 +224,14 @@ type (primitive or non-primitive).  The type of an unboxed tuple looks
 the same.
 </para>
 
+<para>
+Note that when unboxed tuples are enabled,
+<literal>(#</literal> is a single lexeme, so for example when using
+operators like <literal>#</literal> and <literal>#-</literal> you need
+to write <literal>( # )</literal> and <literal>( #- )</literal> rather than
+<literal>(#)</literal> and <literal>(#-)</literal>.
+</para>
+
 <para>
 Unboxed tuples are used for functions that need to return multiple
 values, but they avoid the heap allocation normally associated with