diff --git a/base/compiler/ssair/legacy.jl b/base/compiler/ssair/legacy.jl
index b56a5fb4a6a00..e94bc5f08aa6b 100644
--- a/base/compiler/ssair/legacy.jl
+++ b/base/compiler/ssair/legacy.jl
@@ -59,7 +59,7 @@ Mainly used for testing or interactive use.
 """
 inflate_ir(ci::CodeInfo, linfo::MethodInstance) = inflate_ir!(copy(ci), linfo)
 inflate_ir(ci::CodeInfo, sptypes::Vector{Any}, argtypes::Vector{Any}) = inflate_ir!(copy(ci), sptypes, argtypes)
-inflate_ir(ci::CodeInfo) = inflate_ir(ci, Any[], Any[ Any for i = 1:length(ci.slotflags) ])
+inflate_ir(ci::CodeInfo) = inflate_ir(ci, Any[], Any[ ci.slottypes === nothing ? Any : (ci.slottypes::Vector{Any})[i] for i = 1:length(ci.slotflags) ])
 
 function replace_code_newstyle!(ci::CodeInfo, ir::IRCode, nargs::Int)
     @assert isempty(ir.new_nodes)
diff --git a/base/opaque_closure.jl b/base/opaque_closure.jl
index ac2ae2e8bf3c0..7a539385c9a45 100644
--- a/base/opaque_closure.jl
+++ b/base/opaque_closure.jl
@@ -40,6 +40,21 @@ function compute_ir_rettype(ir::IRCode)
     return Core.Compiler.widenconst(rt)
 end
 
+function compute_oc_argtypes(ir, nargs, isva)
+    argtypes = ir.argtypes[2:end]
+    @assert nargs == length(argtypes)
+    argtypes = Core.Compiler.anymap(Core.Compiler.widenconst, argtypes)
+    if isva
+        lastarg = pop!(argtypes)
+        if lastarg <: Tuple
+            append!(argtypes, lastarg.parameters)
+        else
+            push!(argtypes, Vararg{Any})
+        end
+    end
+    Tuple{argtypes...}
+end
+
 function Core.OpaqueClosure(ir::IRCode, env...;
         nargs::Int = length(ir.argtypes)-1,
         isva::Bool = false,
@@ -57,7 +72,7 @@ function Core.OpaqueClosure(ir::IRCode, env...;
     # NOTE: we need ir.argtypes[1] == typeof(env)
 
     ccall(:jl_new_opaque_closure_from_code_info, Any, (Any, Any, Any, Any, Any, Cint, Any, Cint, Cint, Any),
-          Tuple{ir.argtypes[2:end]...}, Union{}, rt, @__MODULE__, src, 0, nothing, nargs, isva, env)
+        compute_oc_argtypes(ir, nargs, isva), Union{}, rt, @__MODULE__, src, 0, nothing, nargs, isva, env)
 end
 
 function Core.OpaqueClosure(src::CodeInfo, env...)
diff --git a/test/opaque_closure.jl b/test/opaque_closure.jl
index 7fe53812c3a92..530c5b3a844eb 100644
--- a/test/opaque_closure.jl
+++ b/test/opaque_closure.jl
@@ -255,12 +255,18 @@ end
 
 let ci = code_typed((x, y...)->(x, y), (Int, Int))[1][1]
     ir = Core.Compiler.inflate_ir(ci)
-    @test OpaqueClosure(ir; nargs=2, isva=true)(40, 2) === (40, (2,))
-    @test OpaqueClosure(ci)(40, 2) === (40, (2,))
-end
+    let oc = OpaqueClosure(ir; nargs=2, isva=true)
+        @test oc(40, 2) === (40, (2,))
+        @test_throws MethodError oc(1,2,3)
+    end
+    let oc = OpaqueClosure(ci)
+        @test oc(40, 2) === (40, (2,))
+        @test_throws MethodError oc(1,2,3)
+    end
 
-let ci = code_typed((x, y...)->(x, y), (Int, Int))[1][1]
-    ir = Core.Compiler.inflate_ir(ci)
-    @test_throws MethodError OpaqueClosure(ir; nargs=2, isva=true)(1, 2, 3)
-    @test_throws MethodError OpaqueClosure(ci)(1, 2, 3)
+    ir = Core.Compiler.inflate_ir(ci, Any[], Any[Tuple{}, Int, Tuple{Int}])
+    let oc = OpaqueClosure(ir; nargs=2, isva=true)
+        @test oc(40, 2) === (40, (2,))
+        @test_throws MethodError oc(1,2,3)
+    end
 end