diff --git a/libs/langchain/langchain/llms/vertexai.py b/libs/langchain/langchain/llms/vertexai.py
index f2f95035aca..fd6b31f40e3 100644
--- a/libs/langchain/langchain/llms/vertexai.py
+++ b/libs/langchain/langchain/llms/vertexai.py
@@ -288,7 +288,7 @@ class VertexAI(_VertexAICommon, BaseLLM):
             The integer number of tokens in the text.
         """
         try:
-            result = self.client.count_tokens(text)
+            result = self.client.count_tokens([text])
         except AttributeError:
             raise NotImplementedError(
                 "Your google-cloud-aiplatform version didn't implement count_tokens."