diff --git a/src/notebook.jl b/src/notebook.jl
index c9c1036..23b7539 100644
--- a/src/notebook.jl
+++ b/src/notebook.jl
@@ -311,12 +311,12 @@ begin
 		a.rejected_val[] == b.rejected_val[]
 	end
 	
-	Base.hash(p::Promise) = hash((
+	Base.hash(p::Promise, h::UInt) = hash((
 		typeof(p),
 		isready(p),
 		p.resolved_val[],
 		p.rejected_val[],
-	))
+	), h)
 	
 	Base.promote_rule(::Type{Promise{T}}, ::Type{Promise{S}}) where {T,S} = Promise{promote_type(T,S)}
 	function Base.convert(PT::Type{Promise{T}}, p::Promise{S}) where {T,S}
@@ -775,7 +775,7 @@ begin
 		@eval Base.only(a::$RT) = a.value
 		
 		@eval Base.:(==)(a::$RT, b::$RT) = a.value == b.value
-		@eval Base.hash(a::$RT) = hash(a.value, hash($RT))
+		@eval Base.hash(a::$RT, h::UInt) = hash(a.value, hash($RT, h))
 		
 		@eval Base.promote_rule(
 			t1::Type{$RT{T}},