diff --git a/pkgs/development/haskell-modules/generic-builder.nix b/pkgs/development/haskell-modules/generic-builder.nix
index e8195668c41..a6fd7bb0ba9 100644
--- a/pkgs/development/haskell-modules/generic-builder.nix
+++ b/pkgs/development/haskell-modules/generic-builder.nix
@@ -212,7 +212,16 @@ let
   nativeGhcCommand = "${nativeGhc.targetPrefix}ghc";
 
   buildPkgDb = ghcName: packageConfDir: ''
-    if [ -d "$p/lib/${ghcName}/package.conf.d" ]; then
+    # If this dependency has a package database, then copy the contents of it,
+    # unless it is one of our GHCs. These can appear in our dependencies when
+    # we are doing native builds, and they have package databases in them, but
+    # we do not want to copy them over.
+    #
+    # We don't need to, since those packages will be provided by the GHC when
+    # we compile with it, and doing so can result in having multiple copies of
+    # e.g. Cabal in the database with the same name and version, which is
+    # ambiguous.
+    if [ -d "$p/lib/${ghcName}/package.conf.d" ] && [ "$p" != "${ghc}" ] && [ "$p" != "${nativeGhc}" ]; then
       cp -f "$p/lib/${ghcName}/package.conf.d/"*.conf ${packageConfDir}/
       continue
     fi