diff --git a/okapi-core/src/main/kotlin/com/softwaremill/okapi/core/OutboxProcessor.kt b/okapi-core/src/main/kotlin/com/softwaremill/okapi/core/OutboxProcessor.kt
index 84cc82d..6006e3c 100644
--- a/okapi-core/src/main/kotlin/com/softwaremill/okapi/core/OutboxProcessor.kt
+++ b/okapi-core/src/main/kotlin/com/softwaremill/okapi/core/OutboxProcessor.kt
@@ -18,7 +18,7 @@ import java.time.Duration
  * fire-flush-await — making per-entry timing meaningless). Use
  * [OutboxProcessorListener.onBatchProcessed] when you need batch-level timing.
  */
-class OutboxProcessor(
+class OutboxProcessor @JvmOverloads constructor(
     private val store: OutboxStore,
     private val entryProcessor: OutboxEntryProcessor,
     private val listener: OutboxProcessorListener? = null,
diff --git a/okapi-core/src/test/java/com/softwaremill/okapi/core/JavaOutboxProcessorConstruction.java b/okapi-core/src/test/java/com/softwaremill/okapi/core/JavaOutboxProcessorConstruction.java
new file mode 100644
index 0000000..17234de
--- /dev/null
+++ b/okapi-core/src/test/java/com/softwaremill/okapi/core/JavaOutboxProcessorConstruction.java
@@ -0,0 +1,26 @@
+package com.softwaremill.okapi.core;
+
+/**
+ * Java-side guard for {@code @JvmOverloads} on {@link OutboxProcessor}'s constructor.
+ *
+ * <p>These call sites compile only if {@code OutboxProcessor} exposes the shorter,
+ * default-omitting constructors to Java. Drop {@code @JvmOverloads} and okapi-core's test
+ * compilation fails right here — which is the point: a Kotlin-only test keeps compiling
+ * (Kotlin fills defaults at the call site) and would hide the regression. {@code
+ * OutboxProcessorJavaInteropTest} calls these so the guard also runs.
+ */
+public final class JavaOutboxProcessorConstruction {
+
+    private JavaOutboxProcessorConstruction() {}
+
+    /** {@code OutboxProcessor(store, entryProcessor)} — listener and clock default. */
+    public static OutboxProcessor withStoreAndProcessor(OutboxStore store, OutboxEntryProcessor entryProcessor) {
+        return new OutboxProcessor(store, entryProcessor);
+    }
+
+    /** {@code OutboxProcessor(store, entryProcessor, listener)} — clock defaults. */
+    public static OutboxProcessor withListener(
+            OutboxStore store, OutboxEntryProcessor entryProcessor, OutboxProcessorListener listener) {
+        return new OutboxProcessor(store, entryProcessor, listener);
+    }
+}
diff --git a/okapi-core/src/test/kotlin/com/softwaremill/okapi/core/OutboxProcessorJavaInteropTest.kt b/okapi-core/src/test/kotlin/com/softwaremill/okapi/core/OutboxProcessorJavaInteropTest.kt
new file mode 100644
index 0000000..64649b7
--- /dev/null
+++ b/okapi-core/src/test/kotlin/com/softwaremill/okapi/core/OutboxProcessorJavaInteropTest.kt
@@ -0,0 +1,46 @@
+package com.softwaremill.okapi.core
+
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.nulls.shouldNotBeNull
+import java.time.Clock
+import java.time.Instant
+
+/**
+ * Runs the Java call sites in [JavaOutboxProcessorConstruction], which compile only when
+ * [OutboxProcessor]'s constructor carries `@JvmOverloads`. The real guard is that Java source
+ * compiling — okapi-core has no other Java interop test, which is why the missing annotation
+ * regressed unnoticed. The stubs are inert: the constructor only stores its arguments.
+ */
+class OutboxProcessorJavaInteropTest :
+    FunSpec({
+        val store =
+            object : OutboxStore {
+                override fun persist(entry: OutboxEntry) = entry
+
+                override fun claimPending(limit: Int) = emptyList<OutboxEntry>()
+
+                override fun updateAfterProcessing(entry: OutboxEntry) = entry
+
+                override fun removeDeliveredBefore(time: Instant, limit: Int) = 0
+
+                override fun findOldestCreatedAt(statuses: Set<OutboxStatus>) = emptyMap<OutboxStatus, Instant>()
+
+                override fun countByStatuses() = emptyMap<OutboxStatus, Long>()
+            }
+        val entryProcessor =
+            OutboxEntryProcessor(
+                deliverer =
+                object : MessageDeliverer {
+                    override val type = "stub"
+
+                    override fun deliver(entry: OutboxEntry) = DeliveryResult.Success
+                },
+                retryPolicy = RetryPolicy(maxRetries = 3),
+                clock = Clock.systemUTC(),
+            )
+
+        test("Java can construct OutboxProcessor with trailing defaults omitted (@JvmOverloads)") {
+            JavaOutboxProcessorConstruction.withStoreAndProcessor(store, entryProcessor).shouldNotBeNull()
+            JavaOutboxProcessorConstruction.withListener(store, entryProcessor, null).shouldNotBeNull()
+        }
+    })