diff --git a/hledger-lib/Hledger/Utils/Debug.hs b/hledger-lib/Hledger/Utils/Debug.hs
index 5b4f68d7f..a5071b509 100644
--- a/hledger-lib/Hledger/Utils/Debug.hs
+++ b/hledger-lib/Hledger/Utils/Debug.hs
@@ -184,7 +184,7 @@ import Control.Monad.IO.Class (MonadIO, liftIO)
 import Data.List hiding (uncons)
 -- import Debug.Breakpoint
 import Debug.Trace (trace, traceIO, traceShowId)
-#ifdef DEBUG
+#ifdef GHCDEBUG
 import GHC.Debug.Stub (pause, withGhcDebug)
 #endif
 import Safe (readDef)
@@ -224,11 +224,12 @@ debugLevel = case dropWhile (/="--debug") progArgs of
                    _                                   -> 0
 
 -- | Whether ghc-debug support is included in this build, and if so, how it will behave.
--- When hledger is built with the @debug@ cabal flag (off by default),
+-- When hledger is built with the @ghcdebug@ cabal flag (off by default, because of extra deps),
 -- it can listen (on unix ?) for connections from ghc-debug clients like ghc-debug-brick,
 -- for pausing/resuming the program and inspecting memory usage and profile information.
 --
--- This is enabled by running hledger with a negative --debug level, with three different modes:
+-- With a ghc-debug-supporting build, ghc-debug can be enabled by running hledger with
+-- a negative --debug level. There are three different modes:
 -- --debug=-1 - run normally (can be paused/resumed by a ghc-debug client),
 -- --debug=-2 - pause and await client commands at program start (not useful currently),
 -- --debug=-3 - pause and await client commands at program end.
@@ -244,7 +245,7 @@ data GhcDebugMode =
 -- | Is the hledger-lib package built with ghc-debug support ?
 ghcDebugSupportedInLib :: Bool
 ghcDebugSupportedInLib =
-#ifdef DEBUG
+#ifdef GHCDEBUG
   True
 #else
   False
@@ -254,6 +255,7 @@ ghcDebugSupportedInLib =
 -- See GhcDebugMode.
 ghcDebugMode :: GhcDebugMode
 ghcDebugMode =
+#ifdef GHCDEBUG
   case debugLevel of
     _ | not ghcDebugSupportedInLib -> GDNotSupported
     (-1) -> GDNoPause
@@ -261,11 +263,14 @@ ghcDebugMode =
     (-3) -> GDPauseAtEnd
     _    -> GDDisabled
     -- keep synced with GhcDebugMode
+#else
+  GDNotSupported
+#endif
 
 -- | When ghc-debug support has been built into the program and enabled at runtime with --debug=-N,
 -- this calls ghc-debug's withGhcDebug; otherwise it's a no-op.
 withGhcDebug' =
-#ifdef DEBUG
+#ifdef GHCDEBUG
   if ghcDebugMode > GDDisabled then withGhcDebug else id
 #else
   id
@@ -274,7 +279,7 @@ withGhcDebug' =
 -- | When ghc-debug support has been built into the program, this calls ghc-debug's pause, otherwise it's a no-op.
 ghcDebugPause' :: IO ()
 ghcDebugPause' =
-#ifdef DEBUG
+#ifdef GHCDEBUG
   pause
 #else
   return ()
diff --git a/hledger-lib/hledger-lib.cabal b/hledger-lib/hledger-lib.cabal
index 7399a194e..2d02b98b4 100644
--- a/hledger-lib/hledger-lib.cabal
+++ b/hledger-lib/hledger-lib.cabal
@@ -46,7 +46,7 @@ source-repository head
   location: https://github.com/simonmichael/hledger
 
 flag debug
-  description: Build with support for attaching a ghc-debug client
+  description: Build with GHC 9.10+'s stack traces enabled
   manual: True
   default: False
 
@@ -172,8 +172,6 @@ library
         pager >=0.1.1.0
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
 
 test-suite doctest
   type: exitcode-stdio-1.0
@@ -237,8 +235,6 @@ test-suite doctest
         pager >=0.1.1.0
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
   if impl(ghc >= 9.0) && impl(ghc < 9.2)
     buildable: False
 
@@ -305,5 +301,3 @@ test-suite unittest
         pager >=0.1.1.0
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
diff --git a/hledger-lib/package.yaml b/hledger-lib/package.yaml
index 10b7a71c6..f3ca3aa57 100644
--- a/hledger-lib/package.yaml
+++ b/hledger-lib/package.yaml
@@ -97,9 +97,14 @@ ghc-options:
 
 flags:
   debug:
-    description: Build with support for attaching a ghc-debug client
+    description: Build with GHC 9.10+'s stack traces enabled
     default: false
     manual:  true
+# bitrotted
+#  ghcdebug:
+#    description: Build with support for attaching a ghc-debug client
+#    default: false
+#    manual:  true
 
 when:
 - condition: (!(os(windows)))
@@ -107,8 +112,10 @@ when:
   - pager >=0.1.1.0
 - condition: (flag(debug))
   cpp-options: -DDEBUG
-  dependencies:
-  - ghc-debug-stub >=0.6.0.0 && <0.7
+# - condition: (flag(ghcdebug))
+#   cpp-options: -DGHCDEBUG
+#   dependencies:
+#   - ghc-debug-stub >=0.6.0.0 && <0.7
 
 source-dirs: 
 #- other/ledger-parse
diff --git a/hledger-ui/Hledger/UI/Main.hs b/hledger-ui/Hledger/UI/Main.hs
index 0c5a6e72e..fda3c3413 100644
--- a/hledger-ui/Hledger/UI/Main.hs
+++ b/hledger-ui/Hledger/UI/Main.hs
@@ -82,13 +82,18 @@ hledgerUiMain = withGhcDebug' $ withProgName "hledger-ui.log" $ do  -- force Hle
   dbg1IO "args" progArgs
   dbg1IO "debugLevel" debugLevel
 
-  -- try to encourage user's $PAGER to properly display ANSI (in command line help)
-  usecolor <- useColorOnStdout
-  when usecolor setupPager
-
-  opts@UIOpts{uoCliOpts=copts@CliOpts{inputopts_=iopts,rawopts_=rawopts}} <- getHledgerUIOpts
+  opts1@UIOpts{uoCliOpts=copts@CliOpts{inputopts_=iopts,rawopts_=rawopts}} <- getHledgerUIOpts
   -- when (debug_ $ cliopts_ opts) $ printf "%s\n" prognameandversion >> printf "opts: %s\n" (show opts)
 
+  usecolor <- useColorOnStdout
+  -- When ANSI colour/styling is available and enabled, encourage user's $PAGER to use it (for command line help).
+  when usecolor setupPager
+  -- And when it's not, disable colour in the TUI ?
+  -- Theme.hs's themes currently hard code various colours and styles provided by vty,
+  -- which probably are disabled automatically when terminal doesn't support them.
+  -- But we'll at least force hledger-ui's theme to a monochrome one.
+  let opts = if usecolor then opts1 else opts1{uoTheme=Just "terminal"}
+
   -- always generate forecasted periodic transactions; their visibility will be toggled by the UI.
   let copts' = copts{inputopts_=iopts{forecast_=forecast_ iopts <|> Just nulldatespan}}
 
diff --git a/hledger-ui/Hledger/UI/UIOptions.hs b/hledger-ui/Hledger/UI/UIOptions.hs
index f3ffc0b70..5573f3b0a 100644
--- a/hledger-ui/Hledger/UI/UIOptions.hs
+++ b/hledger-ui/Hledger/UI/UIOptions.hs
@@ -33,7 +33,7 @@ prognameandversion :: String
 prognameandversion =
   versionStringWith
   $$tGitInfoCwdTry
-#ifdef DEBUG
+#ifdef GHCDEBUG
   True
 #else
   False
diff --git a/hledger-ui/hledger-ui.cabal b/hledger-ui/hledger-ui.cabal
index 489fe5168..3aca91f8c 100644
--- a/hledger-ui/hledger-ui.cabal
+++ b/hledger-ui/hledger-ui.cabal
@@ -40,7 +40,7 @@ source-repository head
   location: https://github.com/simonmichael/hledger
 
 flag debug
-  description: Build with support for attaching a ghc-debug client
+  description: Build with GHC 9.10+'s stack traces enabled
   manual: True
   default: False
 
@@ -107,8 +107,6 @@ library
   default-language: Haskell2010
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
   if os(windows)
     build-depends:
         vty-windows >=0.2.0.1 && <0.3.0.0
@@ -130,7 +128,5 @@ executable hledger-ui
   default-language: Haskell2010
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
   if flag(threaded)
     ghc-options: -threaded -with-rtsopts=-T
diff --git a/hledger-ui/package.yaml b/hledger-ui/package.yaml
index f31507749..d3c225475 100644
--- a/hledger-ui/package.yaml
+++ b/hledger-ui/package.yaml
@@ -38,9 +38,14 @@ flags:
     default: true
     manual:  false
   debug:
-    description: Build with support for attaching a ghc-debug client
+    description: Build with GHC 9.10+'s stack traces enabled
     default: false
     manual:  true
+# bitrotted
+#  ghcdebug:
+#    description: Build with support for attaching a ghc-debug client
+#    default: false
+#    manual:  true
 
 cpp-options: -DVERSION="1.40.99"
 
@@ -58,8 +63,10 @@ dependencies:
 when:
 - condition: (flag(debug))
   cpp-options: -DDEBUG
-  dependencies:
-  - ghc-debug-stub >=0.6.0.0 && <0.7
+# - condition: (flag(ghcdebug))
+#   cpp-options: -DGHCDEBUG
+#   dependencies:
+#   - ghc-debug-stub >=0.6.0.0 && <0.7
 
  # curses is required to build terminfo for vty for hledger-ui.
  # On POSIX systems it might be not present.
diff --git a/hledger-web/Hledger/Web/WebOptions.hs b/hledger-web/Hledger/Web/WebOptions.hs
index 18aae9bd8..5a0375e1b 100644
--- a/hledger-web/Hledger/Web/WebOptions.hs
+++ b/hledger-web/Hledger/Web/WebOptions.hs
@@ -43,7 +43,7 @@ prognameandversion :: String
 prognameandversion =
   versionStringWith
   $$tGitInfoCwdTry
-#ifdef DEBUG
+#ifdef GHCDEBUG
   True
 #else
   False
diff --git a/hledger-web/hledger-web.cabal b/hledger-web/hledger-web.cabal
index c3e2d03b0..463a42d86 100644
--- a/hledger-web/hledger-web.cabal
+++ b/hledger-web/hledger-web.cabal
@@ -113,7 +113,7 @@ source-repository head
   location: https://github.com/simonmichael/hledger
 
 flag debug
-  description: Build with support for attaching a ghc-debug client
+  description: Build with GHC 9.10+'s stack traces enabled
   manual: True
   default: False
 
@@ -214,8 +214,6 @@ library
     ghc-options: -O0
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
 
 executable hledger-web
   main-is: main.hs
@@ -236,8 +234,6 @@ executable hledger-web
     ghc-options: -O0
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
   if flag(library-only)
     buildable: False
   if flag(threaded)
@@ -261,5 +257,3 @@ test-suite test
     ghc-options: -O0
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
diff --git a/hledger-web/package.yaml b/hledger-web/package.yaml
index 13a3d9d7c..fd01e9fac 100644
--- a/hledger-web/package.yaml
+++ b/hledger-web/package.yaml
@@ -60,9 +60,14 @@ flags:
     default: true
     manual:  false
   debug:
-    description: Build with support for attaching a ghc-debug client
+    description: Build with GHC 9.10+'s stack traces enabled
     default: false
     manual:  true
+# bitrotted
+#  ghcdebug:
+#    description: Build with support for attaching a ghc-debug client
+#    default: false
+#    manual:  true
 
 ghc-options:
 - -Wall
@@ -82,8 +87,10 @@ when:
   ghc-options: -O0
 - condition: (flag(debug))
   cpp-options: -DDEBUG
-  dependencies:
-  - ghc-debug-stub >=0.6.0.0 && <0.7
+# - condition: (flag(ghcdebug))
+#   cpp-options: -DGHCDEBUG
+#   dependencies:
+#   - ghc-debug-stub >=0.6.0.0 && <0.7
 
 dependencies:
 - base >=4.14 && <4.21
diff --git a/hledger/Hledger/Cli/CliOptions.hs b/hledger/Hledger/Cli/CliOptions.hs
index 8678516af..5b9f8e546 100644
--- a/hledger/Hledger/Cli/CliOptions.hs
+++ b/hledger/Hledger/Cli/CliOptions.hs
@@ -134,7 +134,7 @@ prognameandversion :: String
 prognameandversion =
   versionStringWith
   $$tGitInfoCwdTry
-#ifdef DEBUG
+#ifdef GHCDEBUG
   True
 #else
   False
diff --git a/hledger/hledger.cabal b/hledger/hledger.cabal
index 968478546..d31a0a7cb 100644
--- a/hledger/hledger.cabal
+++ b/hledger/hledger.cabal
@@ -93,7 +93,7 @@ source-repository head
   location: https://github.com/simonmichael/hledger
 
 flag debug
-  description: Build with GHC 9.10+'s stack traces enabled, and with support for attaching a ghc-debug client
+  description: Build with GHC 9.10+'s stack traces enabled
   manual: True
   default: False
 
@@ -198,8 +198,6 @@ library
         terminfo
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
 
 executable hledger
   main-is: hledger-cli.hs
@@ -252,8 +250,6 @@ executable hledger
         terminfo
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
   if flag(threaded)
     ghc-options: -threaded -with-rtsopts=-T
 
@@ -307,8 +303,6 @@ test-suite unittest
         terminfo
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
 
 benchmark bench
   type: exitcode-stdio-1.0
@@ -362,5 +356,3 @@ benchmark bench
         terminfo
   if (flag(debug))
     cpp-options: -DDEBUG
-    build-depends:
-        ghc-debug-stub >=0.6.0.0 && <0.7
diff --git a/hledger/package.yaml b/hledger/package.yaml
index 0f517b54f..76da38bcd 100644
--- a/hledger/package.yaml
+++ b/hledger/package.yaml
@@ -100,9 +100,14 @@ flags:
     default: true
     manual:  false
   debug:
-    description: Build with GHC 9.10+'s stack traces enabled, and with support for attaching a ghc-debug client
+    description: Build with GHC 9.10+'s stack traces enabled
     default: false
     manual:  true
+# bitrotted
+#  ghcdebug:
+#    description: Build with support for attaching a ghc-debug client
+#    default: false
+#    manual:  true
 
 ghc-options:
 - -Wall
@@ -157,8 +162,10 @@ when:
   - terminfo
 - condition: (flag(debug))
   cpp-options: -DDEBUG
-  dependencies:
-  - ghc-debug-stub >=0.6.0.0 && <0.7
+# - condition: (flag(ghcdebug))
+#   cpp-options: -DGHCDEBUG
+#   dependencies:
+#   - ghc-debug-stub >=0.6.0.0 && <0.7
 
 library:
   cpp-options: -DVERSION="1.40.99"