diff --git a/Cabal/src/Distribution/Simple/Haddock.hs b/Cabal/src/Distribution/Simple/Haddock.hs
index 784894325cb..f06824b24a9 100644
--- a/Cabal/src/Distribution/Simple/Haddock.hs
+++ b/Cabal/src/Distribution/Simple/Haddock.hs
@@ -821,6 +821,13 @@ renderArgs verbosity tmpFileOpts version comp platform args k = do
         else k (renderedArgs, result)
   where
     outputDir = (unDir $ argOutputDir args)
+    isNotArgContents = isNothing (flagToMaybe $ argContents args)
+    isNotArgIndex = isNothing (flagToMaybe $ argIndex args)
+    isArgGenIndex = fromFlagOrDefault False (argGenIndex args)
+    -- Haddock, when generating HTML, does not generate an index if the options
+    -- --use-contents or --use-index are passed to it. See
+    -- https://haskell-haddock.readthedocs.io/en/latest/invoking.html#cmdoption-use-contents
+    isIndexGenerated = isArgGenIndex && isNotArgContents && isNotArgIndex
     result =
       intercalate ", "
         . map
@@ -828,7 +835,7 @@ renderArgs verbosity tmpFileOpts version comp platform args k = do
               outputDir
                 </> case o of
                   Html
-                    | fromFlagOrDefault False (argGenIndex args) ->
+                    | isIndexGenerated ->
                         "index.html"
                   Html
                     | otherwise ->
diff --git a/changelog.d/pr-9332 b/changelog.d/pr-9332
new file mode 100644
index 00000000000..c5d4c3d4ac4
--- /dev/null
+++ b/changelog.d/pr-9332
@@ -0,0 +1,4 @@
+synopsis: Don't report `index.html` file as created, if not created by Haddock
+packages: Cabal cabal-install
+prs: #9332
+issues: #5120