diff --git a/httpcore5/src/main/java/org/apache/hc/core5/pool/StrictConnPool.java b/httpcore5/src/main/java/org/apache/hc/core5/pool/StrictConnPool.java
index 9801cf82e5..070e462540 100644
--- a/httpcore5/src/main/java/org/apache/hc/core5/pool/StrictConnPool.java
+++ b/httpcore5/src/main/java/org/apache/hc/core5/pool/StrictConnPool.java
@@ -192,7 +192,12 @@ public synchronized PoolEntry<T, C> get(
         final boolean acquiredLock;
 
         try {
-            acquiredLock = this.lock.tryLock(requestTimeout.getDuration(), requestTimeout.getTimeUnit());
+            if (Timeout.isPositive(requestTimeout)) {
+                acquiredLock = this.lock.tryLock(requestTimeout.getDuration(), requestTimeout.getTimeUnit());
+            } else {
+                this.lock.lock();
+                acquiredLock = true;
+            }
         } catch (final InterruptedException interruptedException) {
             Thread.currentThread().interrupt();
             future.cancel();