diff --git a/base/path.jl b/base/path.jl
index d6566f209dd0c..91386cb562d56 100644
--- a/base/path.jl
+++ b/base/path.jl
@@ -514,12 +514,16 @@ function relpath(path::String, startpath::String = ".")
     curdir = "."
     pardir = ".."
     path == startpath && return curdir
-    path_drive, path_without_drive = splitdrive(path)
-    startpath_drive, startpath_without_drive = splitdrive(startpath)
-    path_arr  = split(abspath(path_without_drive),      path_separator_re)
-    start_arr = split(abspath(startpath_without_drive), path_separator_re)
     if Sys.iswindows()
-        lowercase(path_drive) != lowercase(startpath_drive) && return abspath(path)
+        path_drive, path_without_drive = splitdrive(path)
+        startpath_drive, startpath_without_drive = splitdrive(startpath)
+        isempty(startpath_drive) && (startpath_drive = path_drive) # by default assume same as path drive
+        uppercase(path_drive) == uppercase(startpath_drive) || return abspath(path) # if drives differ return first path
+        path_arr  = split(abspath(path_drive * path_without_drive),      path_separator_re)
+        start_arr = split(abspath(path_drive * startpath_without_drive), path_separator_re)
+    else
+        path_arr  = split(abspath(path),      path_separator_re)
+        start_arr = split(abspath(startpath), path_separator_re)
     end
     i = 0
     while i < min(length(path_arr), length(start_arr))
diff --git a/test/path.jl b/test/path.jl
index ca772e24d41de..e263b7c7db917 100644
--- a/test/path.jl
+++ b/test/path.jl
@@ -290,6 +290,10 @@
             # Additional cases
             @test_throws ArgumentError relpath(S("$(sep)home$(sep)user$(sep)dir_withendsep$(sep)"), "")
             @test_throws ArgumentError relpath(S(""), S("$(sep)home$(sep)user$(sep)dir_withendsep$(sep)"))
+
+            # issue 40237
+            path = "..$(sep)a$(sep)b$(sep)c"
+            @test relpath(abspath(path)) == path
         end
         test_relpath()
     end