diff --git a/mkdocs/docs/en/documentation/metrics.md b/mkdocs/docs/en/documentation/metrics.md
index 134e027..83c5cce 100644
--- a/mkdocs/docs/en/documentation/metrics.md
+++ b/mkdocs/docs/en/documentation/metrics.md
@@ -109,7 +109,7 @@ For example, we want to add a common tag for all metrics:
     ```kotlin
     @Module
     interface MetricsConfigModule {
-        fun commonTagsInit(): PrometheusMeterRegistryInitializer? {
+        fun commonTagsInit(): PrometheusMeterRegistryInitializer {
             return PrometheusMeterRegistryInitializer {
                 it.config().commonTags("tag", "value")
                 it
diff --git a/mkdocs/docs/ru/documentation/metrics.md b/mkdocs/docs/ru/documentation/metrics.md
index 7333609..cdde11b 100644
--- a/mkdocs/docs/ru/documentation/metrics.md
+++ b/mkdocs/docs/ru/documentation/metrics.md
@@ -109,7 +109,7 @@
     ```kotlin
     @Module
     interface MetricsConfigModule {
-        fun commonTagsInit(): PrometheusMeterRegistryInitializer? {
+        fun commonTagsInit(): PrometheusMeterRegistryInitializer {
             return PrometheusMeterRegistryInitializer {
                 it.config().commonTags("tag", "value")
                 it