diff --git a/winpr/include/winpr/collections.h b/winpr/include/winpr/collections.h
index c775c1bee..d5cdca560 100644
--- a/winpr/include/winpr/collections.h
+++ b/winpr/include/winpr/collections.h
@@ -102,6 +102,9 @@ WINPR_API BOOL ArrayList_IsFixedSized(wArrayList* arrayList);
 WINPR_API BOOL ArrayList_IsReadOnly(wArrayList* arrayList);
 WINPR_API BOOL ArrayList_IsSynchronized(wArrayList* arrayList);
 
+WINPR_API BOOL ArrayList_Lock(wArrayList* arrayList);
+WINPR_API BOOL ArrayList_Unlock(wArrayList* arrayList);
+
 WINPR_API void* ArrayList_GetItem(wArrayList* arrayList, int index);
 WINPR_API void ArrayList_SetItem(wArrayList* arrayList, int index, void* obj);
 
@@ -112,7 +115,7 @@ WINPR_API int ArrayList_Add(wArrayList* arrayList, void* obj);
 WINPR_API void ArrayList_Insert(wArrayList* arrayList, int index, void* obj);
 
 WINPR_API void ArrayList_Remove(wArrayList* arrayList, void* obj);
-WINPR_API void ArrayList_RemoveAt(wArrayList* arrayList, int index, void* obj);
+WINPR_API void ArrayList_RemoveAt(wArrayList* arrayList, int index);
 
 WINPR_API int ArrayList_IndexOf(wArrayList* arrayList, void* obj, int startIndex, int count);
 WINPR_API int ArrayList_LastIndexOf(wArrayList* arrayList, void* obj, int startIndex, int count);
diff --git a/winpr/libwinpr/utils/collections/ArrayList.c b/winpr/libwinpr/utils/collections/ArrayList.c
index d91baf6e3..bde6520e1 100644
--- a/winpr/libwinpr/utils/collections/ArrayList.c
+++ b/winpr/libwinpr/utils/collections/ArrayList.c
@@ -79,6 +79,24 @@ BOOL ArrayList_IsSynchronized(wArrayList* arrayList)
 	return arrayList->synchronized;
 }
 
+/**
+ * Lock access to the ArrayList
+ */
+
+BOOL ArrayList_Lock(wArrayList* arrayList)
+{
+	return (WaitForSingleObject(arrayList->mutex, INFINITE) == WAIT_OBJECT_0) ? TRUE : FALSE;
+}
+
+/**
+ * Unlock access to the ArrayList
+ */
+
+BOOL ArrayList_Unlock(wArrayList* arrayList)
+{
+	return ReleaseMutex(arrayList->mutex);
+}
+
 /**
  * Gets the element at the specified index.
  */
@@ -87,17 +105,11 @@ void* ArrayList_GetItem(wArrayList* arrayList, int index)
 {
 	void* obj = NULL;
 
-	if (arrayList->synchronized)
-		WaitForSingleObject(arrayList->mutex, INFINITE);
-
 	if ((index >= 0) && (index < arrayList->size))
 	{
 		obj = arrayList->array[index];
 	}
 
-	if (arrayList->synchronized)
-		ReleaseMutex(arrayList->mutex);
-
 	return obj;
 }
 
@@ -107,16 +119,10 @@ void* ArrayList_GetItem(wArrayList* arrayList, int index)
 
 void ArrayList_SetItem(wArrayList* arrayList, int index, void* obj)
 {
-	if (arrayList->synchronized)
-		WaitForSingleObject(arrayList->mutex, INFINITE);
-
 	if ((index >= 0) && (index < arrayList->size))
 	{
 		arrayList->array[index] = obj;
 	}
-
-	if (arrayList->synchronized)
-		ReleaseMutex(arrayList->mutex);
 }
 
 /**
@@ -129,9 +135,6 @@ void ArrayList_SetItem(wArrayList* arrayList, int index, void* obj)
 
 void ArrayList_Shift(wArrayList* arrayList, int index, int count)
 {
-	if (arrayList->synchronized)
-		WaitForSingleObject(arrayList->mutex, INFINITE);
-
 	if (count > 0)
 	{
 		if (arrayList->size + count > arrayList->capacity)
@@ -140,17 +143,14 @@ void ArrayList_Shift(wArrayList* arrayList, int index, int count)
 			arrayList->array = (void**) realloc(arrayList->array, sizeof(void*) * arrayList->capacity);
 		}
 
-		MoveMemory(&arrayList->array[index + count], &arrayList->array[index], count);
+		MoveMemory(&arrayList->array[index + count], &arrayList->array[index], (arrayList->size - index) * sizeof(void*));
 		arrayList->size += count;
 	}
 	else if (count < 0)
 	{
-		MoveMemory(&arrayList->array[index + count], &arrayList->array[index], count);
+		MoveMemory(&arrayList->array[index + count], &arrayList->array[index], (arrayList->size - index) * sizeof(void*));
 		arrayList->size += count;
 	}
-
-	if (arrayList->synchronized)
-		ReleaseMutex(arrayList->mutex);
 }
 
 /**
@@ -252,7 +252,7 @@ void ArrayList_Remove(wArrayList* arrayList, void* obj)
  * Removes the element at the specified index of the ArrayList.
  */
 
-void ArrayList_RemoveAt(wArrayList* arrayList, int index, void* obj)
+void ArrayList_RemoveAt(wArrayList* arrayList, int index)
 {
 	if (arrayList->synchronized)
 		WaitForSingleObject(arrayList->mutex, INFINITE);
diff --git a/winpr/libwinpr/utils/test/CMakeLists.txt b/winpr/libwinpr/utils/test/CMakeLists.txt
index d34853252..e5d6dc04c 100644
--- a/winpr/libwinpr/utils/test/CMakeLists.txt
+++ b/winpr/libwinpr/utils/test/CMakeLists.txt
@@ -6,6 +6,7 @@ set(${MODULE_PREFIX}_DRIVER ${MODULE_NAME}.c)
 
 set(${MODULE_PREFIX}_TESTS
 	TestQueue.c
+	TestArrayList.c
 	TestCmdLine.c)
 
 create_test_sourcelist(${MODULE_PREFIX}_SRCS
diff --git a/winpr/libwinpr/utils/test/TestArrayList.c b/winpr/libwinpr/utils/test/TestArrayList.c
new file mode 100644
index 000000000..59a8e7e72
--- /dev/null
+++ b/winpr/libwinpr/utils/test/TestArrayList.c
@@ -0,0 +1,50 @@
+
+#include <winpr/crt.h>
+#include <winpr/tchar.h>
+#include <winpr/collections.h>
+
+int TestArrayList(int argc, char* argv[])
+{
+	int index;
+	int count;
+	wArrayList* arrayList;
+
+	arrayList = ArrayList_New(TRUE);
+
+	for (index = 0; index < 10; index++)
+	{
+		ArrayList_Add(arrayList, (void*) (size_t) index);
+	}
+
+	count = ArrayList_Count(arrayList);
+
+	printf("ArrayList count: %d\n", count);
+
+	index = ArrayList_IndexOf(arrayList, (void*) (size_t) 6, -1, -1);
+
+	printf("ArrayList index: %d\n", index);
+
+	if (index != 6)
+		return -1;
+
+	ArrayList_Insert(arrayList, 5, (void*) (size_t) 100);
+
+	index = ArrayList_IndexOf(arrayList, (void*) (size_t) 6, -1, -1);
+	printf("ArrayList index: %d\n", index);
+
+	if (index != 7)
+		return -1;
+
+	ArrayList_Remove(arrayList, (void*) (size_t) 100);
+
+	index = ArrayList_IndexOf(arrayList, (void*) (size_t) 6, -1, -1);
+	printf("ArrayList index: %d\n", index);
+
+	if (index != 6)
+		return -1;
+
+	ArrayList_Clear(arrayList);
+	ArrayList_Free(arrayList);
+
+	return 0;
+}