diff --git a/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs b/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs
index 94eeff6d23d..65fcfe0691e 100644
--- a/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs
+++ b/cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs
@@ -97,10 +97,10 @@ instance Ord ProjectConfigPath where
                     if buildOS == Windows
                         then
                             Windows.joinPath $ Windows.splitDirectories
-                            [if c == Posix.pathSeparator then Windows.pathSeparator else c| c <- p]
+                            [if Posix.isPathSeparator c then Windows.pathSeparator else c| c <- p]
                         else
                             Posix.joinPath $ Posix.splitDirectories
-                            [if c == Windows.pathSeparator then Posix.pathSeparator else c| c <- p]
+                            [if Windows.isPathSeparator c then Posix.pathSeparator else c| c <- p]
 
             aPaths = splitPath <$> as
             bPaths = splitPath <$> bs