diff --git a/pisi/build.py b/pisi/build.py
index e5bc915f..e903f298 100644
--- a/pisi/build.py
+++ b/pisi/build.py
@@ -285,9 +285,23 @@ class Builder:
     def check_build_dependencies(self):
         """fail if dependencies not satisfied"""
 
+        build_deps = set(self.spec.source.buildDependencies)
+
+        if not ctx.get_option('bypass_safety'):
+            if ctx.componentdb.has_component('system.devel'):
+                build_deps_names = set([x.package for x in build_deps])
+                devel_deps_names = set(ctx.componentdb.get_component('system.devel').packages)
+                extra_names = devel_deps_names - build_deps_names
+                ctx.ui.warning(_('Safety switch: following extra packages in system.devel will be installed: ') +
+                           util.strlist(extra_names))
+                extra_deps = [dependency.Dependency(package = x) for x in extra_names]
+                build_deps = build_deps.union(extra_deps)
+            else:
+                ctx.ui.warning(_('Safety switch: the component system.devel cannot be found'))
+
         # find out the build dependencies that are not satisfied...
         dep_unsatis = []
-        for dep in self.spec.source.buildDependencies:
+        for dep in build_deps:
             if not dependency.installed_satisfies_dep(dep):
                 dep_unsatis.append(dep)
     
diff --git a/pisi/cli/commands.py b/pisi/cli/commands.py
index 4ec1ad41..e85287f6 100644
--- a/pisi/cli/commands.py
+++ b/pisi/cli/commands.py
@@ -361,6 +361,8 @@ class PackageOp(Command):
         p = self.parser
         p.add_option("-B", "--ignore-comar", action="store_true",
                      default=False, help=_("bypass comar configuration agent"))
+        p.add_option("-S", "--bypass-safety", action="store_true",
+                     default=False, help=_("bypass safety switch"))
         ignoredep_opt(self)
 
     def init(self):
diff --git a/pisi/operations.py b/pisi/operations.py
index 82333d24..b2504bcc 100644
--- a/pisi/operations.py
+++ b/pisi/operations.py
@@ -180,7 +180,7 @@ def expand_components(A):
         if ctx.componentdb.has_component(x):
             Ap = Ap.union(ctx.componentdb.get_component(x).packages)
         else:
-            Ap.append(x)
+            Ap.add(x)
     return Ap
 
 def install_pkg_names(A):
@@ -379,6 +379,16 @@ def remove(A):
     
     # filter packages that are not installed
     A_0 = A = expand_components(set(A))
+
+    if not ctx.get_option('bypass_safety'):
+        if ctx.componentdb.has_component('system.base'):
+            refused = A.intersection(set(ctx.componentdb.get_component('system.base').packages))
+            ctx.ui.warning(_('Safety switch: cannot remove the following packages in system.base: ' +
+                           util.strlist(list(refused))))
+            A = A - set(ctx.componentdb.get_component('system.base').packages)
+        else:
+            ctx.ui.warning(_('Safety switch: the component system.base cannot be found'))
+
     Ap = []
     for x in A:
         if ctx.installdb.is_installed(x):
diff --git a/pisi/specfile.py b/pisi/specfile.py
index 0ec570ef..7564ddee 100644
--- a/pisi/specfile.py
+++ b/pisi/specfile.py
@@ -168,7 +168,8 @@ class Package:
     t_License = [ [autoxml.String], autoxml.optional]
     t_Icon = [ autoxml.String, autoxml.optional]
     t_RuntimeDependencies = [ [Dependency], autoxml.optional]
-    t_Files = [ [Path], autoxml.optional]    
+    t_ComponentDependencies = [ [autoxml.String], autoxml.optional, "RuntimeDependencies/Component"]
+    t_Files = [ [Path], autoxml.optional]
     t_Conflicts = [ [autoxml.String], autoxml.optional, "Conflicts/Package"]
     t_ProvidesComar = [ [ComarProvide], autoxml.optional, "Provides/COMAR"]
     #t_RequiresComar = [ [autoxml.String], autoxml.mandatory, "Requires/COMAR"]