diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out
index a3143ff9ffd..90847323f09 100644
--- a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.out
@@ -1,5 +1,6 @@
 # cabal v2-build
-Warning: <ROOT>/else.project, else.project: Unrecognized section '_' on line 3
+Warnings found while parsing the project file, else.project:
+ - dir-else/else.config: Unrecognized section '_' on line 3
 # Multiline string marking:
 # ^When using configuration from:$
 # ^  - else.project$
@@ -8,3 +9,25 @@ Warning: <ROOT>/else.project, else.project: Unrecognized section '_' on line 3
 # ^  - The package location 'no-pkg-here' does not exist.$
 # Pseudo multiline string marking:
 # ^When using configuration from:   - else.project   - dir-else/else.config The following errors occurred:   - The package location 'no-pkg-here' does not exist.$
+# cabal v2-build
+Error: [Cabal-7090]
+Error parsing project file cabal.project:3:
+ - Failed to parse 'if(_)' with error:
+     "<condition>" (line 1, column 1): unexpected SecArgName (Position 1 4) "_"
+# cabal v2-build
+Error: [Cabal-7090]
+Error parsing project file dir-if/if.config:3:
+ - dir-if/if.config
+     imported by: if.project
+   Failed to parse 'if(_)' with error:
+     "<condition>" (line 1, column 1): unexpected SecArgName (Position 1 4) "_"
+# cabal v2-build
+Error: [Cabal-7090]
+Error parsing project file dir-elif/elif.config:4:
+ - dir-elif/elif.config
+     imported by: elif.project
+   Failed to parse 'elif(_)' with error:
+     "<condition>" (line 1, column 1): unexpected SecArgName (Position 1 6) "_"
+# cabal v2-build
+Warnings found while parsing the project file, else.project:
+ - dir-else/else.config: Unrecognized section '_' on line 3
diff --git a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs
index 021f69a8bda..6dfff2dd915 100644
--- a/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/ProjectImport/ParseErrorProvenance/cabal.test.hs
@@ -27,16 +27,16 @@ main = cabalTest . recordMode RecordMarked $ do
   assertOutputDoesNotContain "imported by:" outDefault
 
   outIf <- fails $ cabal' "v2-build" [ "all", "--dry-run", "--project-file=if.project" ]
-  assertOutputContains "Error parsing project file dir-if/if.config:3" outIf
+  assertOutputContains (normalizeWindowsOutput "Error parsing project file dir-if/if.config:3") outIf
   assertOutputContains "imported by:" outIf
 
   outElif <- fails $ cabal' "v2-build" [ "all", "--dry-run", "--project-file=elif.project" ]
-  assertOutputContains "Error parsing project file dir-elif/elif.config:4" outElif
+  assertOutputContains (normalizeWindowsOutput "Error parsing project file dir-elif/elif.config:4") outElif
   assertOutputContains "imported by:" outElif
 
   outElse <- fails $ cabal' "v2-build" [ "all", "--dry-run", "--project-file=else.project" ]
   assertOutputContains "Warnings found while parsing the project file, else.project:" outElse
-  assertOutputContains "- dir-else/else.config: Unrecognized section '_' on line 3" outElse
+  assertOutputContains (normalizeWindowsOutput "- dir-else/else.config: Unrecognized section '_' on line 3") outElse
   assertOutputContains "When using configuration from:" outElse
 
   return ()
diff --git a/cabal-testsuite/src/Test/Cabal/Prelude.hs b/cabal-testsuite/src/Test/Cabal/Prelude.hs
index daa5472c9d0..2606b9123fb 100644
--- a/cabal-testsuite/src/Test/Cabal/Prelude.hs
+++ b/cabal-testsuite/src/Test/Cabal/Prelude.hs
@@ -1127,6 +1127,9 @@ flakyIfCI ticket m = do
 flakyIfWindows :: IssueID -> TestM a -> TestM a
 flakyIfWindows ticket m = flakyIf isWindows ticket m
 
+normalizeWindowsOutput :: String -> String
+normalizeWindowsOutput = if isWindows then map (\x -> case x of '/' -> '\\'; _ -> x) else id
+
 getOpenFilesLimit :: TestM (Maybe Integer)
 #ifdef mingw32_HOST_OS
 -- No MS-specified limit, was determined experimentally on Windows 10 Pro x64,