diff --git a/lib/roo/excel.rb b/lib/roo/excel.rb
index 92a1e357..97e30bb9 100644
--- a/lib/roo/excel.rb
+++ b/lib/roo/excel.rb
@@ -19,7 +19,7 @@ class Roo::Excel < Roo::GenericSpreadsheet
   def initialize(filename, packed = nil, file_warning = :error)
     file_type_check(filename,'.xls','an Excel', file_warning, packed)
     make_tmpdir do |tmpdir|
-      filename = open_from_uri(filename, tmpdir) if filename[0,7] == "http://"
+      filename = open_from_uri(filename, tmpdir) if uri?(filename)
       filename = open_from_stream(filename[7..-1], tmpdir) if filename[0,7] == "stream:"
       filename = unzip(filename, tmpdir) if packed == :zip
 
diff --git a/lib/roo/excel2003xml.rb b/lib/roo/excel2003xml.rb
index b35cdb7b..c2b9dbd6 100644
--- a/lib/roo/excel2003xml.rb
+++ b/lib/roo/excel2003xml.rb
@@ -10,7 +10,7 @@ class Roo::Excel2003XML < Roo::GenericSpreadsheet
   # values for packed: :zip
   def initialize(filename, packed=nil, file_warning=:error)
     make_tmpdir do |tmpdir|
-      filename = open_from_uri(filename, tmpdir) if filename[0,7] == "http://"
+      filename = open_from_uri(filename, tmpdir) if uri?(filename)
       filename = unzip(filename, tmpdir) if packed == :zip
 
       file_type_check(filename,'.xml','an Excel 2003 XML', file_warning)
diff --git a/lib/roo/excelx.rb b/lib/roo/excelx.rb
index 94404ac0..34bd4beb 100644
--- a/lib/roo/excelx.rb
+++ b/lib/roo/excelx.rb
@@ -87,7 +87,7 @@ class Roo::Excelx < Roo::GenericSpreadsheet
   def initialize(filename, packed=nil, file_warning = :error) #, create = false)
     file_type_check(filename,'.xlsx','an Excel-xlsx', file_warning, packed)
     make_tmpdir do |tmpdir|
-      filename = open_from_uri(filename, tmpdir) if filename[0,7] == "http://"
+      filename = open_from_uri(filename, tmpdir) if uri?(filename)
       filename = unzip(filename, tmpdir) if packed == :zip
       @cells_read = Hash.new
       @filename = filename
diff --git a/lib/roo/generic_spreadsheet.rb b/lib/roo/generic_spreadsheet.rb
index 2ed5c8f3..d42d288c 100644
--- a/lib/roo/generic_spreadsheet.rb
+++ b/lib/roo/generic_spreadsheet.rb
@@ -626,6 +626,10 @@ def normalize(row,col)
     return row,col
   end
 
+  def uri?(filename)
+    filename.start_with?("http://", "https://")
+  end
+
   def open_from_uri(uri, tmpdir)
     require 'open-uri'
     response = ''
diff --git a/lib/roo/openoffice.rb b/lib/roo/openoffice.rb
index b890395f..2f7fbc12 100644
--- a/lib/roo/openoffice.rb
+++ b/lib/roo/openoffice.rb
@@ -37,7 +37,7 @@ def process_zipfile(tmpdir, zip, path='')
   def initialize(filename, packed=nil, file_warning=:error, tmpdir_root=nil)
     file_type_check(filename,'.ods','an Roo::Openoffice', file_warning, packed)
     make_tmpdir(tmpdir_root) do |tmpdir|
-      filename = open_from_uri(filename, tmpdir) if filename[0,7] == "http://"
+      filename = open_from_uri(filename, tmpdir) if uri?(filename)
       filename = unzip(filename, tmpdir) if packed == :zip
       @cells_read = Hash.new
       #TODO: @cells_read[:default] = false