diff --git a/text.cabal b/text.cabal
index 82ad1c37..45dc6464 100644
--- a/text.cabal
+++ b/text.cabal
@@ -76,16 +76,21 @@ flag developer
 flag simdutf
   description: use simdutf library, causes Data.Text.Internal.Validate.Simd to be exposed
   default: True
+  manual: True
 
 flag pure-haskell
   description: Don't use text's standard C routines
     When this flag is true, text will use pure Haskell variants of the
     routines. This is not recommended except for use with GHC's JavaScript
     backend.
+
+    NB: This feature is not fully implemented. Several C routines are still in
+    use.
   default: False
+  manual: True
 
 library
-  if flag(pure-haskell)
+  if arch(javascript) || flag(pure-haskell)
     cpp-options: -DPURE_HASKELL
     c-sources:  cbits/is_ascii.c
                 cbits/measure_off.c
@@ -98,7 +103,7 @@ library
 
   hs-source-dirs: src
 
-  if flag(simdutf)
+  if flag(simdutf) && !(arch(javascript) || flag(pure-haskell))
     exposed-modules: Data.Text.Internal.Validate.Simd
     include-dirs: simdutf
     cxx-sources: simdutf/simdutf.cpp
@@ -146,14 +151,6 @@ library
   if flag(simdutf) && os(netbsd) && impl(ghc < 9.4)
     build-depends: base < 0
 
-  -- Naturally, pure-haskell precludes simdutf
-  if flag(pure-haskell) && flag(simdutf)
-    build-depends: base < 0
-
-  -- The JavaScript backend doesn't support C code
-  if arch(javascript) && flag(pure-haskell)
-    build-depends: base < 0
-
   exposed-modules:
     Data.Text
     Data.Text.Array