diff --git a/src/clj_hl7_fhir/core.clj b/src/clj_hl7_fhir/core.clj
index 2855471..c955d2d 100644
--- a/src/clj_hl7_fhir/core.clj
+++ b/src/clj_hl7_fhir/core.clj
@@ -34,7 +34,7 @@
   "wraps code that performs FHIR operations such that each FHIR HTTP request will have
    any extra HTTP headers specified in the given headers map."
   [headers & body]
-  `(binding [*extra-headers* headers]
+  `(binding [*extra-headers* ~headers]
      ~@body))
 
 (defn- ->fhir-resource-name [x]