diff --git a/Project.toml b/Project.toml
index a28cb5a8..9ef95106 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "BenchmarkTools"
 uuid = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
-version = "1.6.1"
+version = "1.6.2"
 
 [deps]
 Compat = "34da2185-b29b-5c13-b0c7-acf172513d20"
diff --git a/src/serialization.jl b/src/serialization.jl
index 5aa7cced..c3358018 100644
--- a/src/serialization.jl
+++ b/src/serialization.jl
@@ -29,6 +29,19 @@ function JSON.lower(x::Union{values(SUPPORTED_TYPES)...})
     return [string(nameof(typeof(x))), d]
 end
 
+# Special support is needed for JSON@1, because it doesn't know how to support
+# NTuple{N,String} as a dictionary key.
+#
+# Upstream issue: https://github.com/JuliaIO/JSON.jl/issues/399
+#
+# This method may be removed if the upstream issue is fixed.
+function JSON.lower(x::BenchmarkGroup)
+    d = Dict{String,Any}(
+        "data" => Dict(string(k) => v for (k, v) in x.data), "tags" => x.tags
+    )
+    return ["BenchmarkGroup", d]
+end
+
 # a minimal 'eval' function, mirroring KeyTypes, but being slightly more lenient
 safeeval(@nospecialize x) = x
 safeeval(x::QuoteNode) = x.value
diff --git a/test/SerializationTests.jl b/test/SerializationTests.jl
index e24314a1..3d4ab165 100644
--- a/test/SerializationTests.jl
+++ b/test/SerializationTests.jl
@@ -124,4 +124,11 @@ end
     @test BenchmarkTools.load(json_io) == [params]
 end
 
+@testset "issue_400_tuple_as_dict_key" begin
+    grp = BenchmarkTools.BenchmarkGroup()
+    grp["a", "b"] = BenchmarkTools.BenchmarkGroup()
+    contents = sprint(io -> BenchmarkTools.save(io, grp))
+    @test occursin(""""data":{"(\\\"a\\", \\"b\\")":[""", contents)
+end
+
 end # module