diff --git a/Source/cmListFileLexer.c b/Source/cmListFileLexer.c
index f127adde7..ad5a83d3d 100644
--- a/Source/cmListFileLexer.c
+++ b/Source/cmListFileLexer.c
@@ -381,7 +381,7 @@ struct yy_trans_info
 static yyconst flex_int16_t yy_accept[45] =
     {   0,
         0,    0,    0,    0,   17,    6,   14,    1,    8,    2,
-        6,    3,    4,    6,   15,    9,   11,   12,   13,    6,
+        6,    3,    4,    5,   15,    9,   11,   12,   13,    6,
         0,    6,    0,   14,    2,    0,    5,    6,    9,    0,
        10,    0,    7,    0,    0,    0,    7,    0,    7,    0,
         0,    0,    0,    0
diff --git a/Source/cmListFileLexer.in.l b/Source/cmListFileLexer.in.l
index bd3c1eb27..89f29173a 100644
--- a/Source/cmListFileLexer.in.l
+++ b/Source/cmListFileLexer.in.l
@@ -107,7 +107,7 @@ LEGACY {MAKEVAR}|{UNQUOTED}|\"({MAKEVAR}|{UNQUOTED}|[ \t])*\"
   return 1;
 }
 
-[A-Za-z_][A-Za-z0-9_]+ {
+[A-Za-z_][A-Za-z0-9_]* {
   lexer->token.type = cmListFileLexer_Token_Identifier;
   cmListFileLexerSetToken(lexer, yytext, yyleng);
   lexer->column += yyleng;
diff --git a/Tests/RunCMake/Syntax/OneLetter-stderr.txt b/Tests/RunCMake/Syntax/OneLetter-stderr.txt
new file mode 100644
index 000000000..87c01c71c
--- /dev/null
+++ b/Tests/RunCMake/Syntax/OneLetter-stderr.txt
@@ -0,0 +1 @@
+message
diff --git a/Tests/RunCMake/Syntax/OneLetter.cmake b/Tests/RunCMake/Syntax/OneLetter.cmake
new file mode 100644
index 000000000..3c341fab0
--- /dev/null
+++ b/Tests/RunCMake/Syntax/OneLetter.cmake
@@ -0,0 +1,7 @@
+function(f)
+  g(${ARGN})
+endfunction()
+macro(g)
+  message(${ARGN})
+endmacro()
+f(message)
diff --git a/Tests/RunCMake/Syntax/RunCMakeTest.cmake b/Tests/RunCMake/Syntax/RunCMakeTest.cmake
index 94963f348..2d87328e8 100644
--- a/Tests/RunCMake/Syntax/RunCMakeTest.cmake
+++ b/Tests/RunCMake/Syntax/RunCMakeTest.cmake
@@ -9,6 +9,7 @@ run_cmake(CommandError1)
 run_cmake(String0)
 run_cmake(String1)
 run_cmake(StringNoSpace)
+run_cmake(OneLetter)
 run_cmake(Unquoted0)
 run_cmake(Unquoted1)
 run_cmake(ParenNoSpace)