diff --git a/blackbird/src/main/java/com/fasterxml/jackson/module/blackbird/deser/BBDeserializerModifier.java b/blackbird/src/main/java/com/fasterxml/jackson/module/blackbird/deser/BBDeserializerModifier.java
index 1e196818..260a6e13 100644
--- a/blackbird/src/main/java/com/fasterxml/jackson/module/blackbird/deser/BBDeserializerModifier.java
+++ b/blackbird/src/main/java/com/fasterxml/jackson/module/blackbird/deser/BBDeserializerModifier.java
@@ -222,7 +222,7 @@ private <T> T createSetter(Lookup lookup, Class<T> iface, Class<?> thunkType, Me
                 MethodHandles.lookup(),
                 "accept",
                 MethodType.methodType(iface, thunkType),
-                MethodType.methodType(void.class, Object.class, Object.class),
+                MethodType.methodType(void.class, Object.class, valueType),
                 trampoline,
                 MethodType.methodType(void.class, Object.class, valueType))
             .getTarget().invoke(builtThunk));
diff --git a/blackbird/src/test/java/com/fasterxml/jackson/module/blackbird/failing/BasicDeserialize123Test.java b/blackbird/src/test/java/com/fasterxml/jackson/module/blackbird/deser/BasicDeserialize123Test.java
similarity index 94%
rename from blackbird/src/test/java/com/fasterxml/jackson/module/blackbird/failing/BasicDeserialize123Test.java
rename to blackbird/src/test/java/com/fasterxml/jackson/module/blackbird/deser/BasicDeserialize123Test.java
index de3084a9..8c3bf2b4 100644
--- a/blackbird/src/test/java/com/fasterxml/jackson/module/blackbird/failing/BasicDeserialize123Test.java
+++ b/blackbird/src/test/java/com/fasterxml/jackson/module/blackbird/deser/BasicDeserialize123Test.java
@@ -1,4 +1,4 @@
-package com.fasterxml.jackson.module.blackbird.failing;
+package com.fasterxml.jackson.module.blackbird.deser;
 
 import com.fasterxml.jackson.databind.ObjectMapper;