diff --git a/src/workbook.jl b/src/workbook.jl
index e415937..6e8b78c 100644
--- a/src/workbook.jl
+++ b/src/workbook.jl
@@ -20,7 +20,8 @@ sheetnames(wb::Workbook) = [ s.name for s in wb.sheets ]
 @inline sheetnames(xl::XLSXFile) = sheetnames(xl.workbook)
 
 """
-    hassheet(wb::Workbook, sheetname::AbstractString) :: Bool
+    hassheet(wb::Workbook, sheetname::AbstractString)
+    hassheet(xl::XLSXFile, sheetname::AbstractString)
 
 Returns `true` if `wb` contains a sheet named `sheetname`.
 """