diff --git a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/HttpInterface.kt b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/HttpInterface.kt
index 49d6cc0..3306ba8 100644
--- a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/HttpInterface.kt
+++ b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/HttpInterface.kt
@@ -26,7 +26,7 @@ interface HttpInterface {
         }
     }
 
-    fun transmit(url: String, tx: ByteArray, headers: Array<String>): HttpResponse
+    fun transmit(url: String, tx: ByteArray, headers: List<String>): HttpResponse
     // The LPA is supposed to pass in a list of pkIds supported by the eUICC.
     // HttpInterface is responsible for providing TrustManager implementations that
     // validate based on certificates corresponding to these pkIds
diff --git a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/HttpInterfaceImpl.kt b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/HttpInterfaceImpl.kt
index c1b15f7..d3775fd 100644
--- a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/HttpInterfaceImpl.kt
+++ b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/HttpInterfaceImpl.kt
@@ -26,7 +26,7 @@ class HttpInterfaceImpl(
     override fun transmit(
         url: String,
         tx: ByteArray,
-        headers: Array<String>
+        headers: List<String>
     ): HttpInterface.HttpResponse {
         Log.d(TAG, "transmit(url = $url)")
 
diff --git a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/LocalProfileAssistantImpl.kt b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/LocalProfileAssistantImpl.kt
index c6f3cbf..2343f1a 100644
--- a/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/LocalProfileAssistantImpl.kt
+++ b/libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/LocalProfileAssistantImpl.kt
@@ -63,7 +63,7 @@ class LocalProfileAssistantImpl(
          */
         var lastHttpException: Exception? = null
 
-        override fun transmit(url: String, tx: ByteArray, headers: Array<String>): HttpResponse =
+        override fun transmit(url: String, tx: ByteArray, headers: List<String>): HttpResponse =
             try {
                 httpInterface.transmit(url, tx, headers).also {
                     lastHttpException = null
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c b/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c
index 702ba45..3f2dff1 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/interface-wrapper.c
@@ -26,7 +26,7 @@ void interface_wrapper_init(JNIEnv *env) {
 
     jclass http_class = (*env)->FindClass(env, "net/typeblog/lpac_jni/HttpInterface");
     method_http_transmit = (*env)->GetMethodID(env, http_class, "transmit",
-                                               "(Ljava/lang/String;[B[Ljava/lang/String;)Lnet/typeblog/lpac_jni/HttpInterface$HttpResponse;");
+                                               "(Ljava/lang/String;[BLjava/util/List;)Lnet/typeblog/lpac_jni/HttpInterface$HttpResponse;");
 
     jclass resp_class = (*env)->FindClass(env, "net/typeblog/lpac_jni/HttpInterface$HttpResponse");
     field_resp_rcode = (*env)->GetFieldID(env, resp_class, "rcode", "I");
@@ -95,19 +95,18 @@ http_interface_transmit(struct euicc_ctx *ctx, const char *url, uint32_t *rcode,
     jbyteArray txArr = (*env)->NewByteArray(env, (jsize) tx_len);
     (*env)->SetByteArrayRegion(env, txArr, 0, (jsize) tx_len, (const jbyte *) tx);
 
-    int num_headers = 0;
-    while (headers[num_headers] != NULL) {
-        num_headers++;
-    }
-    jobjectArray headersArr = (*env)->NewObjectArray(env, num_headers, string_class, NULL);
-    for (int i = 0; i < num_headers; i++) {
+    jobject header_list = new_array_list(env);
+    jclass header_list_class = (*env)->GetObjectClass(env, header_list);
+    jmethodID add_header = (*env)->GetMethodID(env, header_list_class, "add", "(Ljava/lang/Object;)Z");
+
+    for (int i = 0; headers[i] != NULL; i++) {
         jstring header = toJString(env, headers[i]);
-        (*env)->SetObjectArrayElement(env, headersArr, i, header);
+        (*env)->CallBooleanMethod(env, header_list, add_header, header);
         (*env)->DeleteLocalRef(env, header);
     }
 
     jobject ret = (*env)->CallObjectMethod(env, LPAC_JNI_CTX(ctx)->http_interface,
-                                           method_http_transmit, jurl, txArr, headersArr);
+                                           method_http_transmit, jurl, txArr, header_list);
     LPAC_JNI_EXCEPTION_RETURN;
     *rcode = (*env)->GetIntField(env, ret, field_resp_rcode);
     jbyteArray rxArr = (jbyteArray) (*env)->GetObjectField(env, ret, field_resp_data);
@@ -116,7 +115,7 @@ http_interface_transmit(struct euicc_ctx *ctx, const char *url, uint32_t *rcode,
     (*env)->GetByteArrayRegion(env, rxArr, 0, (jsize) *rx_len, (jbyte *) *rx);
     (*env)->DeleteLocalRef(env, txArr);
     (*env)->DeleteLocalRef(env, rxArr);
-    (*env)->DeleteLocalRef(env, headersArr);
+    (*env)->DeleteLocalRef(env, header_list);
     (*env)->DeleteLocalRef(env, ret);
     return 0;
 }
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c
index 1b1518d..da714ac 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.c
@@ -17,7 +17,7 @@ static jclass version_class;
 static jmethodID version_constructor;
 
 static jstring empty_string;
-jclass string_class;
+static jclass string_class;
 static jmethodID string_constructor;
 
 jobject bind_static_field(JNIEnv *env, jclass clazz, const char *name, const char *sig) {
diff --git a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h
index dfed36b..cc7c568 100644
--- a/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h
+++ b/libs/lpac-jni/src/main/jni/lpac-jni/lpac-convertor.h
@@ -17,8 +17,6 @@
 #define HASH_SET_CLASS "java/util/HashSet"
 #define ARRAY_LIST_CLASS "java/util/ArrayList"
 
-jclass string_class;
-
 void lpac_convertor_init(JNIEnv *env);
 
 jstring toJString(JNIEnv *env, const char *pat);