diff --git a/tests/distributed/test_pipeline_parallel.py b/tests/distributed/test_pipeline_parallel.py
index e54b8c909f359..83f621ee0f9af 100644
--- a/tests/distributed/test_pipeline_parallel.py
+++ b/tests/distributed/test_pipeline_parallel.py
@@ -156,11 +156,13 @@ def iter_params(self, model_name: str):
     # "internlm/internlm-chat-7b": PPTestSettings.fast(),
     "internlm/internlm2-chat-7b": PPTestSettings.fast(trust_remote_code=True),
     "inceptionai/jais-13b-chat": PPTestSettings.fast(),
+    "ai21labs/Jamba-tiny-dev": PPTestSettings.fast(),
     "meta-llama/Meta-Llama-3-8B": PPTestSettings.detailed(),
     "openbmb/MiniCPM-2B-sft-bf16": PPTestSettings.fast(trust_remote_code=True),
     "openbmb/MiniCPM3-4B": PPTestSettings.fast(trust_remote_code=True),
     # Uses Llama
     # "mistralai/Mistral-7B-Instruct-v0.1": PPTestSettings.fast(),
+    "state-spaces/mamba-130m-hf": PPTestSettings.fast(),
     "mistralai/Mixtral-8x7B-Instruct-v0.1": PPTestSettings.fast(tp_base=4),
     "mosaicml/mpt-7b": PPTestSettings.fast(),
     "nvidia/Minitron-8B-Base": PPTestSettings.fast(),
@@ -178,9 +180,7 @@ def iter_params(self, model_name: str):
     "Qwen/Qwen1.5-MoE-A2.7B-Chat": PPTestSettings.fast(),
     "stabilityai/stablelm-3b-4e1t": PPTestSettings.fast(),
     "bigcode/starcoder2-3b": PPTestSettings.fast(),
-    "upstage/solar-pro-preview-instruct": PPTestSettings.fast(tp_base=2),
-    "ai21labs/Jamba-tiny-dev": PPTestSettings.fast(),
-    "state-spaces/mamba-130m-hf": PPTestSettings.fast()
+    "upstage/solar-pro-preview-instruct": PPTestSettings.fast(tp_base=2)
     # FIXME: Cannot load tokenizer in latest transformers version.
     # Need to use tokenizer from `meta-llama/Llama-2-7b-chat-hf`
     # "xverse/XVERSE-7B-Chat": PPTestSettings.fast(trust_remote_code=True),
@@ -234,6 +234,8 @@ def iter_params(self, model_name: str):
     "OpenGVLab/InternVL2-1B",
     "microsoft/Phi-3-vision-128k-instruct",
     "fixie-ai/ultravox-v0_3",
+    # [LANGUAGE GENERATION - HYBRID ARCH]
+    "ai21labs/Jamba-tiny-dev",
 ]
 
 
diff --git a/vllm/config.py b/vllm/config.py
index 8b4d15a7055b9..5e419be4ec8aa 100644
--- a/vllm/config.py
+++ b/vllm/config.py
@@ -704,10 +704,8 @@ def get_num_layers_by_block_type(
         # Transformers supports layers_block_type @property
         layers_block_type_value = getattr(self.hf_config, "layers_block_type",
                                           [block_type.value] * (end - start))
-        return len([
-            t for t in layers_block_type_value[start:end]
-            if t == block_type.value
-        ])
+        return sum(t == block_type.value
+                   for t in layers_block_type_value[start:end])
 
     def get_multimodal_config(self) -> "MultiModalConfig":
         """
diff --git a/vllm/model_executor/models/jamba.py b/vllm/model_executor/models/jamba.py
index dc1dabe8e478e..5aebbed9f0ba4 100644
--- a/vllm/model_executor/models/jamba.py
+++ b/vllm/model_executor/models/jamba.py
@@ -286,7 +286,7 @@ def __init__(self, *, vllm_config: VllmConfig, prefix: str = ""):
         )
 
         def get_layer(prefix: str):
-            layer_idx = int(prefix.split(".")[-1])
+            layer_idx = int(prefix.rsplit(".", 1)[1])
             layer_class = ALL_DECODER_LAYER_TYPES[
                 config.layers_block_type[layer_idx]]
             return layer_class(