diff --git a/routing/http/server/server.go b/routing/http/server/server.go
index 015ff3d68..d6b78e98e 100644
--- a/routing/http/server/server.go
+++ b/routing/http/server/server.go
@@ -148,6 +148,8 @@ func (s *server) findProviders(w http.ResponseWriter, httpReq *http.Request) {
 }
 
 func writeResult(w http.ResponseWriter, method string, val any) {
+	w.Header().Add("Content-Type", "application/json")
+
 	// keep the marshaling separate from the writing, so we can distinguish bugs (which surface as 500)
 	// from transient network issues (which surface as transport errors)
 	b, err := drjson.MarshalJSONBytes(val)
diff --git a/routing/http/server/server_test.go b/routing/http/server/server_test.go
new file mode 100644
index 000000000..20c5e73e0
--- /dev/null
+++ b/routing/http/server/server_test.go
@@ -0,0 +1,62 @@
+package server
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/ipfs/go-cid"
+	"github.com/ipfs/go-libipfs/routing/http/types"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestHeaders(t *testing.T) {
+	router := &mockContentRouter{}
+	server := httptest.NewServer(Handler(router))
+	t.Cleanup(server.Close)
+	serverAddr := "http://" + server.Listener.Addr().String()
+
+	result := []types.ProviderResponse{
+		&types.ReadBitswapProviderRecord{
+			Protocol: types.BitswapProviderID,
+		},
+	}
+
+	c := "baeabep4vu3ceru7nerjjbk37sxb7wmftteve4hcosmyolsbsiubw2vr6pqzj6mw7kv6tbn6nqkkldnklbjgm5tzbi4hkpkled4xlcr7xz4bq"
+	cb, err := cid.Decode(c)
+	require.NoError(t, err)
+
+	router.On("FindProviders", mock.Anything, cb).
+		Return(result, nil)
+
+	resp, err := http.Get(serverAddr + ProvidePath + c)
+	require.NoError(t, err)
+	require.Equal(t, 200, resp.StatusCode)
+	header := resp.Header.Get("Content-Type")
+	require.Equal(t, "application/json", header)
+
+	resp, err = http.Get(serverAddr + ProvidePath + "BAD_CID")
+	require.NoError(t, err)
+	require.Equal(t, 400, resp.StatusCode)
+	header = resp.Header.Get("Content-Type")
+	require.Equal(t, "text/plain; charset=utf-8", header)
+}
+
+type mockContentRouter struct{ mock.Mock }
+
+func (m *mockContentRouter) FindProviders(ctx context.Context, key cid.Cid) ([]types.ProviderResponse, error) {
+	args := m.Called(ctx, key)
+	return args.Get(0).([]types.ProviderResponse), args.Error(1)
+}
+func (m *mockContentRouter) ProvideBitswap(ctx context.Context, req *BitswapWriteProvideRequest) (time.Duration, error) {
+	args := m.Called(ctx, req)
+	return args.Get(0).(time.Duration), args.Error(1)
+}
+
+func (m *mockContentRouter) Provide(ctx context.Context, req *WriteProvideRequest) (types.ProviderResponse, error) {
+	args := m.Called(ctx, req)
+	return args.Get(0).(types.ProviderResponse), args.Error(1)
+}