diff --git a/slf4j-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala b/slf4j-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala
index 4c54bd793..0348257cc 100644
--- a/slf4j-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala
+++ b/slf4j-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala
@@ -18,6 +18,8 @@ package zio.logging.slf4j.bridge
 import org.slf4j.impl.ZioLoggerFactory
 import zio.{ Runtime, ZIO, ZLayer }
 
+import java.util.concurrent.locks.ReentrantLock
+
 object Slf4jBridge {
 
   /**
@@ -46,11 +48,17 @@ object Slf4jBridge {
   def initialize(nameAnnotationKey: String): ZLayer[Any, Nothing, Unit] =
     Runtime.enableCurrentFiber ++ layer(nameAnnotationKey)
 
+  private val initLock: ReentrantLock = new ReentrantLock()
+
   private def layer(nameAnnotationKey: String): ZLayer[Any, Nothing, Unit] =
     ZLayer {
       ZIO.runtime[Any].flatMap { runtime =>
         ZIO.succeed {
-          ZioLoggerFactory.initialize(new ZioLoggerRuntime(runtime, nameAnnotationKey))
+          initLock.lock()
+          try
+            ZioLoggerFactory.initialize(new ZioLoggerRuntime(runtime, nameAnnotationKey))
+          finally
+            initLock.unlock()
         }
       }
     }
diff --git a/slf4j-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala b/slf4j-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala
index ac71f0609..4d5d2d365 100644
--- a/slf4j-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala
+++ b/slf4j-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala
@@ -5,6 +5,8 @@ import org.slf4j.impl.StaticMarkerBinder
 import zio.test._
 import zio.{ Cause, Chunk, LogLevel, ZIO, ZIOAspect }
 
+import java.util.UUID
+
 object Slf4jBridgeSpec extends ZIOSpecDefault {
 
   final case class LogEntry(
@@ -17,6 +19,17 @@ object Slf4jBridgeSpec extends ZIOSpecDefault {
 
   override def spec =
     suite("Slf4jBridge")(
+      test("parallel init") {
+        val uuids = List.fill(5)(UUID.randomUUID())
+        for {
+          _ <-
+            ZIO.foreachPar(uuids) { u =>
+              ZIO
+                .succeed(org.slf4j.LoggerFactory.getLogger("SLF4J-LOGGER").warn("Test {} {}!", "WARNING", u.toString))
+                .provide(Slf4jBridge.initialize)
+            }
+        } yield assertTrue(true)
+      },
       test("logs through slf4j - legacy logger name annotation key") {
         val testFailure = new RuntimeException("test error")
         for {
diff --git a/slf4j2-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala b/slf4j2-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala
index 51e455425..74ff8897e 100644
--- a/slf4j2-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala
+++ b/slf4j2-bridge/src/main/scala/zio/logging/slf4j/bridge/Slf4jBridge.scala
@@ -17,6 +17,8 @@ package zio.logging.slf4j.bridge
 
 import zio.{ Runtime, ZIO, ZLayer }
 
+import java.util.concurrent.locks.ReentrantLock
+
 object Slf4jBridge {
 
   /**
@@ -29,14 +31,20 @@ object Slf4jBridge {
    */
   def initializeWithoutFiberRefPropagation: ZLayer[Any, Nothing, Unit] = layer
 
+  private val initLock: ReentrantLock = new ReentrantLock()
+
   private def layer: ZLayer[Any, Nothing, Unit] =
     ZLayer {
       ZIO.runtime[Any].flatMap { runtime =>
         ZIO.succeed {
-          org.slf4j.LoggerFactory
-            .getILoggerFactory()
-            .asInstanceOf[LoggerFactory]
-            .attacheRuntime(new ZioLoggerRuntime(runtime))
+          initLock.lock()
+          try
+            org.slf4j.LoggerFactory
+              .getILoggerFactory()
+              .asInstanceOf[LoggerFactory]
+              .attacheRuntime(new ZioLoggerRuntime(runtime))
+          finally
+            initLock.unlock()
         }
       }
     }
diff --git a/slf4j2-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala b/slf4j2-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala
index 34af42417..2bc04eefa 100644
--- a/slf4j2-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala
+++ b/slf4j2-bridge/src/test/scala/zio/logging/slf4j/bridge/Slf4jBridgeSpec.scala
@@ -3,6 +3,8 @@ package zio.logging.slf4j.bridge
 import zio.test._
 import zio.{ Cause, Chunk, LogLevel, ZIO, ZIOAspect }
 
+import java.util.UUID
+
 object Slf4jBridgeSpec extends ZIOSpecDefault {
 
   final case class LogEntry(
@@ -15,6 +17,17 @@ object Slf4jBridgeSpec extends ZIOSpecDefault {
 
   override def spec =
     suite("Slf4jBridge")(
+      test("parallel init") {
+        val uuids = List.fill(5)(UUID.randomUUID())
+        for {
+          _ <-
+            ZIO.foreachPar(uuids) { u =>
+              ZIO
+                .succeed(org.slf4j.LoggerFactory.getLogger("SLF4J-LOGGER").warn("Test {} {}!", "WARNING", u.toString))
+                .provide(Slf4jBridge.initialize)
+            }
+        } yield assertTrue(true)
+      },
       test("logs through slf4j") {
         val testFailure = new RuntimeException("test error")
         for {