diff --git a/pkgs/build-support/cc-wrapper/default.nix b/pkgs/build-support/cc-wrapper/default.nix
index aca96f58ed97d..ed8d41be806a6 100644
--- a/pkgs/build-support/cc-wrapper/default.nix
+++ b/pkgs/build-support/cc-wrapper/default.nix
@@ -40,7 +40,7 @@ let
   libc_lib = if libc == null then null else getLib libc;
   cc_solib = getLib cc;
   # The wrapper scripts use 'cat' and 'grep', so we may need coreutils.
-  coreutils_bin = if nativeTools then "" else getBin coreutils;
+  coreutils_bin = if (nativeTools || targetPlatform.isWindows) then "" else getBin coreutils;
 
   default_cxx_stdlib_compile = optionalString (targetPlatform.isLinux && !(cc.isGNU or false) && !nativeTools && cc ? gcc)
     "-isystem $(echo -n ${cc.gcc}/include/c++/*) -isystem $(echo -n ${cc.gcc}/include/c++/*)/$(${cc.gcc}/bin/gcc -dumpmachine)";
diff --git a/pkgs/development/compilers/ghc/8.4.3.nix b/pkgs/development/compilers/ghc/8.4.3.nix
index 0f5a43d57eda4..fae5dfce1cf3c 100644
--- a/pkgs/development/compilers/ghc/8.4.3.nix
+++ b/pkgs/development/compilers/ghc/8.4.3.nix
@@ -32,6 +32,8 @@
   ghcFlavour ? stdenv.lib.optionalString (targetPlatform != hostPlatform) "perf-cross"
 }:
 
+assert !enableIntegerSimple -> gmp != null;
+
 let
   inherit (bootPkgs) ghc;
 
@@ -46,8 +48,7 @@ let
     include mk/flavours/\$(BuildFlavour).mk
     endif
     DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
-  '' + stdenv.lib.optionalString enableIntegerSimple ''
-    INTEGER_LIBRARY = integer-simple
+    INTEGER_LIBRARY = ${if enableIntegerSimple then "integer-simple" else "integer-gmp"}
   '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
     Stage1Only = ${if targetPlatform.system == hostPlatform.system then "NO" else "YES"}
     CrossCompilePrefix = ${targetPrefix}
@@ -133,9 +134,11 @@ stdenv.mkDerivation (rec {
   configureFlags = [
     "--datadir=$doc/share/doc/ghc"
     "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
-  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && ! enableIntegerSimple) [
+  ] ++ (if (targetPlatform == hostPlatform && !enableIntegerSimple) then [
     "--with-gmp-includes=${gmp.dev}/include" "--with-gmp-libraries=${gmp.out}/lib"
-  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc" && !targetPlatform.isWindows) [
+  ] else [
+    "--with-gmp-includes=${targetPackages.gmp.dev}/include" "--with-gmp-libraries=${targetPackages.gmp.out}/lib"
+  ]) ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc" && !targetPlatform.isWindows) [
     "--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
   ] ++ stdenv.lib.optionals (targetPlatform != hostPlatform) [
     "--enable-bootstrap-with-devel-snapshot"
diff --git a/pkgs/development/haskell-modules/generic-builder.nix b/pkgs/development/haskell-modules/generic-builder.nix
index d1304c7969499..e9d95d5e3f52c 100644
--- a/pkgs/development/haskell-modules/generic-builder.nix
+++ b/pkgs/development/haskell-modules/generic-builder.nix
@@ -112,7 +112,7 @@ let
                      main = defaultMain
                    '';
 
-  hasActiveLibrary = isLibrary && (enableStaticLibraries || enableSharedLibraries || enableLibraryProfiling);
+  hasActiveLibrary = isLibrary && (enableStaticLibraries || enableSharedLibraries || enableLibraryProfiling || hostPlatform.isWindows);
 
   # We cannot enable -j<n> parallelism for libraries because GHC is far more
   # likely to generate a non-determistic library ID in that case. Further
@@ -138,12 +138,12 @@ let
   buildFlagsString = optionalString (buildFlags != []) (" " + concatStringsSep " " buildFlags);
 
   defaultConfigureFlags = [
-    "--verbose" "--prefix=$out" "--libdir=\\$prefix/lib/\\$compiler" "--libsubdir=\\$pkgid"
+    "--verbose" "--prefix=$out" "--libdir=\\$prefix/\\$compiler" "--libsubdir=\\$pkgid"
     (optionalString enableSeparateDataOutput "--datadir=$data/share/${ghc.name}")
     (optionalString enableSeparateDocOutput "--docdir=${docdir "$doc"}")
     "--with-gcc=$CC" # Clang won't work without that extra information.
     "--package-db=$packageConfDir"
-    (optionalString (enableSharedExecutables && stdenv.isLinux) "--ghc-option=-optl=-Wl,-rpath=$out/lib/${ghc.name}/${pname}-${version}")
+    (optionalString (enableSharedExecutables && stdenv.isLinux) "--ghc-option=-optl=-Wl,-rpath=$out/${ghc.name}/${pname}-${version}")
     (optionalString (enableSharedExecutables && stdenv.isDarwin) "--ghc-option=-optl=-Wl,-headerpad_max_install_names")
     (optionalString enableParallelBuilding "--ghc-option=-j$NIX_BUILD_CORES")
     (optionalString useCpphs "--with-cpphs=${cpphs}/bin/cpphs --ghc-options=-cpp --ghc-options=-pgmP${cpphs}/bin/cpphs --ghc-options=-optP--cpp")
@@ -209,8 +209,8 @@ let
   nativeGhcCommand = "${nativeGhc.targetPrefix}ghc";
 
   buildPkgDb = ghcName: packageConfDir: ''
-    if [ -d "$p/lib/${ghcName}/package.conf.d" ]; then
-      cp -f "$p/lib/${ghcName}/package.conf.d/"*.conf ${packageConfDir}/
+    if [ -d "$p/${ghcName}/package.conf.d" ]; then
+      cp -f "$p/${ghcName}/package.conf.d/"*.conf ${packageConfDir}/
       continue
     fi
   '';
@@ -294,14 +294,14 @@ stdenv.mkDerivation ({
   ''
   # only use the links hack if we're actually building dylibs. otherwise, the
   # "dynamic-library-dirs" point to nonexistent paths, and the ln command becomes
-  # "ln -s $out/lib/links", which tries to recreate the links dir and fails
+  # "ln -s $out/lib-links", which tries to recreate the links dir and fails
   + (optionalString (stdenv.isDarwin && (enableSharedLibraries || enableSharedExecutables)) ''
     # Work around a limit in the macOS Sierra linker on the number of paths
     # referenced by any one dynamic library:
     #
     # Create a local directory with symlinks of the *.dylib (macOS shared
     # libraries) from all the dependencies.
-    local dynamicLinksDir="$out/lib/links"
+    local dynamicLinksDir="$out/lib-links"
     mkdir -p $dynamicLinksDir
     for d in $(grep dynamic-library-dirs "$packageConfDir/"*|awk '{print $2}'|sort -u); do
       ln -s "$d/"*.dylib $dynamicLinksDir
@@ -379,7 +379,7 @@ stdenv.mkDerivation ({
 
     ${if !hasActiveLibrary then "${setupCommand} install" else ''
       ${setupCommand} copy
-      local packageConfDir="$out/lib/${ghc.name}/package.conf.d"
+      local packageConfDir="$out/${ghc.name}/package.conf.d"
       local packageConfFile="$packageConfDir/${pname}-${version}.conf"
       mkdir -p "$packageConfDir"
       ${setupCommand} register --gen-pkg-config=$packageConfFile
@@ -404,7 +404,7 @@ stdenv.mkDerivation ({
     ${optionalString doCoverage "mkdir -p $out/share && cp -r dist/hpc $out/share"}
     ${optionalString (enableSharedExecutables && isExecutable && !isGhcjs && stdenv.isDarwin && stdenv.lib.versionOlder ghc.version "7.10") ''
       for exe in "$out/bin/"* ; do
-        install_name_tool -add_rpath "$out/lib/ghc-${ghc.version}/${pname}-${version}" "$exe"
+        install_name_tool -add_rpath "$out/ghc-${ghc.version}/${pname}-${version}" "$exe"
       done
     ''}
 
diff --git a/pkgs/development/haskell-modules/lib.nix b/pkgs/development/haskell-modules/lib.nix
index c9dc7254800e8..d5e36981ba352 100644
--- a/pkgs/development/haskell-modules/lib.nix
+++ b/pkgs/development/haskell-modules/lib.nix
@@ -234,7 +234,7 @@ rec {
     enableSharedExecutables = false;
     isLibrary = false;
     doHaddock = false;
-    postFixup = "rm -rf $out/lib $out/nix-support $out/share/doc";
+    postFixup = "rm -rf $out/ghc* $out/nix-support $out/share/doc";
   });
 
   /* Build a source distribution tarball instead of using the source files
diff --git a/pkgs/tools/misc/coreutils/default.nix b/pkgs/tools/misc/coreutils/default.nix
index 589c58d0acc02..b13ba656a8a91 100644
--- a/pkgs/tools/misc/coreutils/default.nix
+++ b/pkgs/tools/misc/coreutils/default.nix
@@ -10,6 +10,7 @@
 
 assert aclSupport -> acl != null;
 assert selinuxSupport -> libselinux != null && libsepol != null;
+assert hostPlatform.libc != "msvcrt";
 
 with lib;