diff --git a/.clang-tidy-limits.yml b/.clang-tidy-limits.yml
deleted file mode 100644
index f0b5377..0000000
--- a/.clang-tidy-limits.yml
+++ /dev/null
@@ -1,32 +0,0 @@
-limits:
-  "google-readability-braces-around-statements" : 30
-  "readability-braces-around-statements" : 30
-  "clang-diagnostic-error" : 10
-  "readability-non-const-parameter" : 10
-  "misc-misplaced-const" : 10
-  "clang-diagnostic-typedef-redefinition" : 10
-  "hicpp-braces-around-statements" : 10
-  "clang-diagnostic-int-to-pointer-cast" : 10
-  "hicpp-no-assembler" : 10
-  "readability-else-after-return" : 10
-  "readability-redundant-declaration" : 10
-  "clang-diagnostic-unknown-attributes" : 10
-  "misc-unused-parameters" : 10
-  "readability-inconsistent-declaration-parameter-name" : 10
-  "google-readability-todo" : 10
-  "clang-diagnostic-macro-redefined" : 10
-  "google-readability-casting" : 10
-  "readability-inconsistent-declaration-parameter-name": 10
-  "readability-named-parameter": 10
-  "readability-container-size-empty": 10
-  "modernize-use-using": 10
-  "modernize-use-override": 10
-  "readability-implicit-bool-cast": 10
-  "modernize-use-default-member-init": 10
-  "performance-unnecessary-value-param": 10
-  "modernize-use-equals-default": 10
-  "modernize-use-nullptr": 10
-
-ignore:
-
-
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 3461a4c..aa87863 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -7,6 +7,8 @@ stages:
 
 variables:
   IDF_REPO: ${GITLAB_SSH_SERVER}/idf/esp-idf.git
+  OLDER_IDF: release/v3.1
+  RECENT_IDF: release/v3.3
 
 .add_gh_key_remote: &add_gh_key_remote |
   cit_add_ssh_key "${GH_PUSH_KEY}"
@@ -19,6 +21,23 @@ before_script:
   - source citools/import_functions
   - PATH=$CI_PROJECT_DIR/esp-idf/tools:$PATH
 
+build_with_older_idf:
+  stage: build
+  image: ${CI_DOCKER_REGISTRY}/esp32-ci-env
+  tags:
+    - build
+  dependencies: []
+  script:
+    - cit_add_ssh_key "${GITLAB_KEY}"
+    - git clone "${IDF_REPO}" && cd esp-idf && git checkout ${OLDER_IDF}
+    - ./tools/ci/mirror-submodule-update.sh
+    - export IDF_PATH=$(pwd)
+    - cd $CI_PROJECT_DIR
+    - ./modify_for_legacy_idf.sh ${RECENT_IDF} || true
+    - cd $CI_PROJECT_DIR/examples/tcp
+    - make defconfig
+    - make
+
 build_with_idf:
   stage: build
   image: ${CI_DOCKER_REGISTRY}/esp32-ci-env
@@ -40,17 +59,16 @@ build_with_idf:
     - rm -rf .git
     - cp -r $CI_PROJECT_DIR/.git .
     - git reset --hard $CI_COMMIT_SHA
-    # build one example and capture compile commands/flags for static analysis
+    # capture compile commands/flags for static analysis
     - cd $IDF_PATH/examples/protocols/mqtt/tcp
+    - mkdir -p tidybuild && cd tidybuild
+    - cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ..
+    - mv $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild $CI_PROJECT_DIR/tidybuild
+    # enable pedantic flags for compilation
     - export PEDANTIC_CFLAGS="-Werror -Werror=deprecated-declarations -Werror=unused-variable -Werror=unused-but-set-variable -Werror=unused-function"
     - export EXTRA_CFLAGS=${PEDANTIC_CFLAGS} && export EXTRA_CXXFLAGS=${EXTRA_CFLAGS}
-    - idf.py build
-    - mkdir -p tidybuild
-    - cd tidybuild
-    - cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON ..
-    - cd $CI_PROJECT_DIR
-    - mv $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild $CI_PROJECT_DIR/tidybuild
     # build other examples
+    - cd $IDF_PATH/examples/protocols/mqtt/tcp && idf.py build
     - cd $IDF_PATH/examples/protocols/mqtt/ssl && idf.py build
     - cd $IDF_PATH/examples/protocols/mqtt/ssl_mutual_auth && idf.py build
     - cd $IDF_PATH/examples/protocols/mqtt/ws && idf.py build
@@ -82,9 +100,8 @@ clang_tidy_check:
     - git reset --hard $CI_COMMIT_SHA
     - mv $CI_PROJECT_DIR/tidybuild $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild
     - cd $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild
-    - git clone "${CI_REPORT_TOOLS}"
-    - cd static-analysis-utils
-    - ./generate_report.sh $CI_PROJECT_DIR/.clang-tidy-limits.yml $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild/report $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild/output.xml
+    - git clone $IDF_ANALYSIS_UTILS static_analysis_utils && cd static_analysis_utils
+    - ./generate_report.sh $CI_PROJECT_DIR/static-analysis-rules.yml $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild/report $IDF_PATH/examples/protocols/mqtt/tcp/tidybuild/output.xml
 
 deploy_report:
   stage: deploy_report
@@ -105,6 +122,7 @@ deploy_report:
     - ssh $DOCS_SERVER -x "cd $DOCS_PATH/clang-tidy && tar xzvf $GIT_VER.tar.gz && rm -f latest && ln -s $GIT_VER latest"
     # add link to view the report
     - echo "[static analysis][clang tidy] $CI_DOCKER_REGISTRY/static_analysis/esp-idf/clang-tidy/${GIT_VER}/index.html"
+    - test ! -e ${GIT_VER}/FAILED_RULES || { echo 'Failed static analysis rules!'; cat ${GIT_VER}/FAILED_RULES; exit 1; }
 
 push_master_to_github:
   stage: deploy
diff --git a/include/mqtt_client.h b/include/mqtt_client.h
index 8b05d0b..a347f08 100644
--- a/include/mqtt_client.h
+++ b/include/mqtt_client.h
@@ -19,6 +19,12 @@
 extern "C" {
 #endif
 
+#ifndef ESP_EVENT_DECLARE_BASE
+// Define event loop types if macros not available
+typedef void * esp_event_loop_handle_t;
+typedef void * esp_event_handler_t;
+#endif
+
 typedef struct esp_mqtt_client *esp_mqtt_client_handle_t;
 
 /**
diff --git a/include/mqtt_supported_features.h b/include/mqtt_supported_features.h
index 9a3ab04..3e9fac0 100644
--- a/include/mqtt_supported_features.h
+++ b/include/mqtt_supported_features.h
@@ -27,10 +27,15 @@
  */
 
 #ifdef ESP_IDF_VERSION
+
+#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(3, 3, 0)
+// Features supported from 3.3
+#define MQTT_SUPPORTED_FEATURE_EVENT_LOOP
+#endif
+
 #if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 0, 0)
-
+// Features supported in 4.0
 #define MQTT_SUPPORTED_FEATURE_WS_SUBPROTOCOL
-
 #endif
 #endif
 
diff --git a/lib/mqtt_outbox.c b/lib/mqtt_outbox.c
index d92bfb6..8b1ff8d 100644
--- a/lib/mqtt_outbox.c
+++ b/lib/mqtt_outbox.c
@@ -152,7 +152,6 @@ int outbox_delete_expired(outbox_handle_t outbox, int current_tick, int timeout)
     STAILQ_FOREACH_SAFE(item, outbox, next, tmp) {
         if (current_tick - item->tick > timeout) {
             STAILQ_REMOVE(outbox, item, outbox_item, next);
-            printf("free message\n");
             free(item->buffer);
             free(item);
             deleted_items ++;
@@ -167,7 +166,9 @@ int outbox_get_size(outbox_handle_t outbox)
     int siz = 0;
     outbox_item_handle_t item;
     STAILQ_FOREACH(item, outbox, next) {
-        siz += item->len;
+        // Suppressing "use after free" warning as this could happen only if queue is in inconsistent state
+        // which never happens if STAILQ interface used
+        siz += item->len; // NOLINT(clang-analyzer-unix.Malloc)
     }
     return siz;
 }
diff --git a/mqtt_client.c b/mqtt_client.c
index a3e2fce..a95f4b3 100644
--- a/mqtt_client.c
+++ b/mqtt_client.c
@@ -30,11 +30,13 @@
 
 static const char *TAG = "MQTT_CLIENT";
 
+#ifdef MQTT_SUPPORTED_FEATURE_EVENT_LOOP
 /**
  * @brief Define of MQTT Event base
  *
  */
 ESP_EVENT_DEFINE_BASE(MQTT_EVENTS);
+#endif
 
 typedef struct mqtt_state
 {
@@ -55,7 +57,9 @@ typedef struct mqtt_state
 
 typedef struct {
     mqtt_event_callback_t event_handle;
+#ifdef MQTT_SUPPORTED_FEATURE_EVENT_LOOP
     esp_event_loop_handle_t event_loop_handle;
+#endif
     int task_stack;
     int task_prio;
     char *uri;
@@ -226,11 +230,13 @@ esp_err_t esp_mqtt_set_config(esp_mqtt_client_handle_t client, const esp_mqtt_cl
     if (config->event_handle) {
         cfg->event_handle = config->event_handle;
     } else {
+#ifdef MQTT_SUPPORTED_FEATURE_EVENT_LOOP
         esp_event_loop_args_t no_task_loop = {
             .queue_size = 1,
             .task_name = NULL,
         };
         esp_event_loop_create(&no_task_loop, &cfg->event_loop_handle);
+#endif
     }
 
     if (config->refresh_connection_after_ms) {
@@ -564,8 +570,12 @@ static esp_err_t esp_mqtt_dispatch_event(esp_mqtt_client_handle_t client)
     if (client->config->event_handle) {
         return client->config->event_handle(&client->event);
     } else {
+#ifdef MQTT_SUPPORTED_FEATURE_EVENT_LOOP
         esp_event_post_to(client->config->event_loop_handle, MQTT_EVENTS, client->event.event_id, &client->event, sizeof(client->event), portMAX_DELAY);
         return esp_event_loop_run(client->config->event_loop_handle, 0);
+#else
+        return ESP_FAIL;
+#endif
     }
 }
 
@@ -1319,10 +1329,15 @@ esp_err_t esp_mqtt_client_register_event(esp_mqtt_client_handle_t client, esp_mq
     if (client == NULL) {
         return ESP_ERR_INVALID_ARG;
     }
+#ifdef MQTT_SUPPORTED_FEATURE_EVENT_LOOP
     if (client->config->event_handle) {
         ESP_LOGW(TAG, "Registering event loop while event callback is not null, clearing callback");
         client->config->event_handle = NULL;
     }
 
     return esp_event_handler_register_with(client->config->event_loop_handle, MQTT_EVENTS, event, event_handler, event_handler_arg);
+#else
+    ESP_LOGE(TAG, "Registering event handler while event loop not available in IDF version %s", IDF_VER);
+    return ESP_FAIL;
+#endif
 }
diff --git a/static-analysis-rules.yml b/static-analysis-rules.yml
new file mode 100644
index 0000000..bd36de8
--- /dev/null
+++ b/static-analysis-rules.yml
@@ -0,0 +1,9 @@
+limits:
+  "clang-analyzer-core.NullDereference" : 0
+  "clang-analyzer-unix.Malloc" : 0
+
+ignore:
+  - "llvm-header-guard"
+  - "llvm-include-order"
+
+skip: