diff --git a/src/grammar_base.jl b/src/grammar_base.jl
index acc9ef6..8258b15 100644
--- a/src/grammar_base.jl
+++ b/src/grammar_base.jl
@@ -235,7 +235,25 @@ function add_rule!(g::AbstractGrammar, e::Expr)
     return g
 end
 
+
+"""
+    add_rule(grammar, tree)
+
+Extends a given grammar with an `AbstractRuleNode`. The type of the rule is inferred from the root-type.
+# Arguments
+- `grammar::AbstractGrammar`: the grammar to extend
+- `tree::RuleNode`: the Herb tree
+"""
+function add_rule!(grammar::AbstractGrammar, tree::AbstractRuleNode)
+    type = return_type(grammar, tree.ind)
+    new_grammar_rule = rulenode2expr(tree, grammar)
+    add_rule!(grammar, :($type = $new_grammar_rule))
+end
+
+
 """
+    add_rule!(g::AbstractGrammar, p::Real, e::Expr)
+
 Adds a probabilistic derivation rule.
 """
 function add_rule!(g::AbstractGrammar, p::Real, e::Expr)
diff --git a/test/test_csg.jl b/test/test_csg.jl
index 071090b..87e064f 100644
--- a/test/test_csg.jl
+++ b/test/test_csg.jl
@@ -275,4 +275,18 @@
         add_rule!(g, :(A = 2))
         @test g.rules == [:(1 + A), :(2 * B), 1, 1, 2, 2]
     end 
+
+    @testset "Add tree to grammar" begin 
+        g = @cfgrammar begin
+            Number = |(1:2)
+            Number = x
+            Number = Number + Number 
+            Number = Number * Number
+        end
+        hole = Hole(get_domain(g, g.bytype[:Number]))
+        test_ast = RuleNode(4, [RuleNode(1), hole])
+        
+        add_rule!(g, test_ast)
+        @test g.rules[6] == :(1 + Number)
+    end
 end