diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -6,6 +6,8 @@
   * (1.20.3): detect an absolute windows path with a drive letter in a #include
   * (1.20.4): more windows path handling
   * (1.20.5): revert change in 1.20.4
+  * (1.20.6): minor bugfix for crash in obscure corner case
+  * (1.20.7): bugfix for windows drive letter in #include
 
 Version 1.19
 ------------
diff --git a/Language/Preprocessor/Cpphs/ReadFirst.hs b/Language/Preprocessor/Cpphs/ReadFirst.hs
--- a/Language/Preprocessor/Cpphs/ReadFirst.hs
+++ b/Language/Preprocessor/Cpphs/ReadFirst.hs
@@ -38,23 +38,28 @@
 
 readFirst name demand path warn =
     case name of
-       nm@(c:':':_) -> try nm [""]  -- Windows absolute path
-       '/':nm -> try nm   [""]
-       _      -> try name (cons dd (".":path))
+                       -- Windows drive in absolute path
+       c:':':'/':nm -> try nm   (Just (c:':':[])) [""]
+                       -- Windows drive in relative path
+       c:':':nm     -> try nm   (Just (c:':':[])) (cons dd (".":path))
+                       -- unix-like absolute path
+       '/':nm       -> try nm   Nothing           [""]
+                       -- any relative path
+       _            -> try name Nothing           (cons dd (".":path))
   where
     dd = directory demand
     cons x xs = if null x then xs else x:xs
-    try name [] = do
+    try name _ [] = do
         when warn $
           hPutStrLn stderr ("Warning: Can't find file \""++name
                            ++"\" in directories\n\t"
                            ++concat (intersperse "\n\t" (cons dd (".":path)))
                            ++"\n  Asked for by: "++show demand)
         return ("missing file: "++name,"")
-    try name (p:ps) = do
-        let file = cleanPath p++'/':cleanPath name
+    try name drive (p:ps) = do
+        let file = (maybe id (++) drive) $ cleanPath p++'/':cleanPath name
         ok <- doesFileExist file
-        if not ok then try name ps
+        if not ok then try name drive ps
           else do content <- readFileUTF8 file
                   return (file,content)
 
diff --git a/cpphs.cabal b/cpphs.cabal
--- a/cpphs.cabal
+++ b/cpphs.cabal
@@ -1,5 +1,5 @@
 Name: cpphs
-Version: 1.20.6
+Version: 1.20.7
 Copyright: 2004-2017, Malcolm Wallace
 License: LGPL
 License-File: LICENCE-LGPL
diff --git a/cpphs.hs b/cpphs.hs
--- a/cpphs.hs
+++ b/cpphs.hs
@@ -21,7 +21,7 @@
 import Data.List   ( isPrefixOf )
 
 version :: String
-version = "1.20.6"
+version = "1.20.7"
 
 main :: IO ()
 main = do
diff --git a/docs/index.html b/docs/index.html
--- a/docs/index.html
+++ b/docs/index.html
@@ -198,11 +198,11 @@
 <b>Current stable version:</b>
 
 <p>
-cpphs-1.20.6, release date 2017-06-21<br>
+cpphs-1.20.7, release date 2017-06-21<br>
 By HTTP:
 <a href="http://hackage.haskell.org/package/cpphs">Hackage</a>.
 <ul>
-<li> (1.20.6) minor bugfix to avoid a crash in an obscure corner case
+<li> (1.20.7) bugfix for windows drive letters in #includes.
 </ul>
 
 <p>
@@ -224,6 +224,14 @@
 
 <p>
 <b>Older versions:</b>
+
+<p>
+cpphs-1.20.7, release date 2017-06-21<br>
+By HTTP:
+<a href="http://hackage.haskell.org/package/cpphs">Hackage</a>.
+<ul>
+<li> (1.20.7) bugfix for windows drive letters in #includes.
+</ul>
 
 <p>
 cpphs-1.20.6, release date 2017-06-21<br>