diff --git a/pkgs/development/interpreters/ruby/gem.nix b/pkgs/development/interpreters/ruby/gem.nix
index 3e5057ef1d0..bb0bc2e4863 100644
--- a/pkgs/development/interpreters/ruby/gem.nix
+++ b/pkgs/development/interpreters/ruby/gem.nix
@@ -54,7 +54,7 @@ in ruby.stdenv.mkDerivation (attrs // {
 
     for prog in $out/bin/*; do
       wrapProgram "$prog" \
-        --prefix GEM_PATH : "$out/${ruby.gemPath}" \
+        --prefix GEM_PATH : "$out/${ruby.gemPath}:$GEM_PATH" \
         --prefix RUBYLIB : "${rubygems}/lib" \
         --set RUBYOPT rubygems \
         $extraWrapperFlags ''${extraWrapperFlagsArray[@]}
diff --git a/pkgs/development/interpreters/ruby/patches.nix b/pkgs/development/interpreters/ruby/patches.nix
index 3a0a330e6d4..cff21c900f5 100644
--- a/pkgs/development/interpreters/ruby/patches.nix
+++ b/pkgs/development/interpreters/ruby/patches.nix
@@ -43,7 +43,7 @@ in
 
     postInstall = stdenv.lib.optionalString stdenv.isDarwin ''
       cat >> $out/nix-support/setup-hook <<EOF
-        addToSearchPath DYLD_INSERT_LIBRARIES "${v8}/lib/libv8.dylib"
+        export DYLD_INSERT_LIBRARIES="$DYLD_INSERT_LIBRARIES''${!DYLD_INSERT_LIBRARIES:+:}${v8}/lib/libv8.dylib"
       EOF
     '';