diff --git a/src/abstractinterpret/abstractanalyzer.jl b/src/abstractinterpret/abstractanalyzer.jl
index 696117a2c..aa115cbf6 100644
--- a/src/abstractinterpret/abstractanalyzer.jl
+++ b/src/abstractinterpret/abstractanalyzer.jl
@@ -84,7 +84,25 @@ struct AbstractBindingState
     AbstractBindingState(isconst::Bool, maybeundef::Bool, @nospecialize typ) = new(isconst, maybeundef, typ)
     AbstractBindingState(isconst::Bool, maybeundef::Bool) = new(isconst, maybeundef)
 end
-const AbstractBindings = IdDict{Core.BindingPartition,AbstractBindingState}
+
+# `report_package` analyzes signatures concurrently while all task analyzers share a single
+# `binding_states::AbstractBindings` (see `AnalyzerState`). Guard the underlying `IdDict` with
+# a lock so concurrent `setindex!`/rehash cannot corrupt it; the accesses are infrequent
+# (only on global binding assignments and binding-partition lookups), so the uncontended lock
+# cost is negligible.
+struct AbstractBindings
+    bindings::IdDict{Core.BindingPartition,AbstractBindingState}
+    lock::ReentrantLock
+    AbstractBindings() = new(IdDict{Core.BindingPartition,AbstractBindingState}(), ReentrantLock())
+end
+@inline Base.getindex(b::AbstractBindings, partition::Core.BindingPartition) =
+    @lock b.lock b.bindings[partition]
+@inline Base.setindex!(b::AbstractBindings, binding_state::AbstractBindingState, partition::Core.BindingPartition) =
+    (@lock b.lock b.bindings[partition] = binding_state; return b)
+@inline Base.haskey(b::AbstractBindings, partition::Core.BindingPartition) =
+    @lock b.lock haskey(b.bindings, partition)
+@inline Base.get(b::AbstractBindings, partition::Core.BindingPartition, @nospecialize(default)) =
+    @lock b.lock get(b.bindings, partition, default)
 
 """
     mutable struct AnalyzerState
diff --git a/src/abstractinterpret/typeinfer.jl b/src/abstractinterpret/typeinfer.jl
index 032ffdf1e..44bcfbc65 100644
--- a/src/abstractinterpret/typeinfer.jl
+++ b/src/abstractinterpret/typeinfer.jl
@@ -558,18 +558,21 @@ function const_assignment_rt_exct(analyzer::ToplevelAbstractAnalyzer, sv::Infere
         if rt !== Union{}
             # `:const` assignment destructively overrides the binding type
             binding_states = get_binding_states(analyzer)
-            if !isconditional
-                binding_state = AbstractBindingState(true, false, new_binding_typ′[])
-            elseif haskey(binding_states, partition)
-                old_binding_state = binding_states[partition]
-                @assert old_binding_state.isconst && isdefined(old_binding_state, :typ)
-                newmaybeundef = old_binding_state.maybeundef & isconditional
-                newtyp = old_binding_state.typ ⊔ new_binding_typ′[]
-                binding_state = AbstractBindingState(true, newmaybeundef, newtyp)
-            else
-                binding_state = AbstractBindingState(true, true, new_binding_typ′[])
+            binding_state = @lock binding_states.lock begin
+                if !isconditional
+                    new_state = AbstractBindingState(true, false, new_binding_typ′[])
+                elseif haskey(binding_states, partition)
+                    old_binding_state = binding_states[partition]
+                    @assert old_binding_state.isconst && isdefined(old_binding_state, :typ)
+                    newmaybeundef = old_binding_state.maybeundef & isconditional
+                    newtyp = old_binding_state.typ ⊔ new_binding_typ′[]
+                    new_state = AbstractBindingState(true, newmaybeundef, newtyp)
+                else
+                    new_state = AbstractBindingState(true, true, new_binding_typ′[])
+                end
+                binding_states[partition] = new_state
+                new_state
             end
-            binding_states[partition] = binding_state
             # HACK/FIXME Concretize `AbstractBindingState`
             # For top-level analysis implementation reasons, we actually define this
             # `AbstractBindingState` in the analyzed module’s namespace.