3 files changed, 11 insertions, 9 deletions
diff --git a/tasks/libmruby.rake b/tasks/libmruby.rake
index 108f42f59..6f84937fd 100644
--- a/tasks/libmruby.rake
+++ b/tasks/libmruby.rake
@@ -2,14 +2,14 @@ MRuby.each_target do
   file libfile("#{build_dir}/lib/libmruby") => libmruby.flatten do |t|
     archiver.run t.name, t.prerequisites
     open("#{build_dir}/lib/libmruby.flags.mak", 'w') do |f|
-      f.puts 'CFLAGS = "%s"' % cc.all_flags.gsub('"', '\\"') 
+      f.puts 'MRUBY_CFLAGS = "%s"' % cc.all_flags.gsub('"', '\\"') 
 
       gem_flags = gems.map { |g| g.linker.flags }
       gem_library_paths = gems.map { |g| g.linker.library_paths }
-      f.puts 'LDFLAGS = "%s"' % linker.all_flags(gem_library_paths, gem_flags).gsub('"', '\\"') 
+      f.puts 'MRUBY_LDFLAGS = "%s"' % linker.all_flags(gem_library_paths, gem_flags).gsub('"', '\\"') 
 
       gem_libraries = gems.map { |g| g.linker.libraries }
-      f.puts 'LIBS = "%s"' % linker.library_flags(gem_libraries).gsub('"', '\\"') 
+      f.puts 'MRUBY_LIBS = "%s"' % linker.library_flags(gem_libraries).gsub('"', '\\"') 
     end
   end
 end
diff --git a/tasks/mruby_build.rake b/tasks/mruby_build.rake
index b9e0d2749..711f7f024 100644
--- a/tasks/mruby_build.rake
+++ b/tasks/mruby_build.rake
@@ -29,10 +29,6 @@ module MRuby
       conf.instance_eval(&@initializer)
     end
 
-    def toolchain(name)
-      @@toolchains[name.to_s].setup(self)
-    end
-
     def self.load
       Dir.glob("#{File.dirname(__FILE__)}/toolchains/*.rake").each do |file|
         Kernel.load file
@@ -93,7 +89,9 @@ module MRuby
     end
 
     def toolchain(name)
-      Toolchain.toolchains[name.to_s].setup(self)
+      tc = Toolchain.toolchains[name.to_s]
+      fail "Unknown #{name} toolchain" unless tc
+      tc.setup(self)
     end
 
     def build_dir
diff --git a/tasks/mruby_build_gem.rake b/tasks/mruby_build_gem.rake
index ae0a79447..80990773d 100644
--- a/tasks/mruby_build_gem.rake
+++ b/tasks/mruby_build_gem.rake
@@ -2,7 +2,11 @@ module MRuby
   module LoadGems
     def gem(gemdir, &block)
       gemdir = load_external_gem(gemdir) if gemdir.is_a?(Hash)
-      load File.join(gemdir, "mrbgem.rake")
+      gemrake = File.join(gemdir, "mrbgem.rake")
+
+      fail "Can't find #{gemrake}" unless File.exists?(gemrake)
+      load gemrake
+
       Gem.current.dir = gemdir
       Gem.current.build = MRuby::Build.current
       Gem.current.build_config_initializer = block