diff --git a/src/fsharp/lex.fsl b/src/fsharp/lex.fsl
index edd9de972e8..e6dd1a6e397 100644
--- a/src/fsharp/lex.fsl
+++ b/src/fsharp/lex.fsl
@@ -203,8 +203,8 @@ let xint8 = xinteger 'y'
 let xint16 = xinteger 's'
 let xint = xinteger 
 let xint32 = xinteger 'l'
-let floatp = digit ((digit | separator)* digit)? '.' (digit (digit | separator)*)?  
-let floate = digit ((digit | separator)* digit)? ('.' (digit (digit | separator)*)? )? ('e'| 'E') ['+' '-']? digit (digit | separator)*
+let floatp = digit ((digit | separator)* digit)? '.' (digit ((digit | separator)* digit)?)?  
+let floate = digit ((digit | separator)* digit)? ('.' (digit ((digit | separator)* digit)?)? )? ('e'| 'E') ['+' '-']? digit ((digit | separator)* digit)?
 let float = floatp | floate 
 let bignum =  integer ('I'  | 'N' | 'Z' | 'Q' | 'R' | 'G')
 let ieee64 = float