diff --git a/python/mlc_llm/interface/compiler_flags.py b/python/mlc_llm/interface/compiler_flags.py
index 2d0d668672..fb72a8b806 100644
--- a/python/mlc_llm/interface/compiler_flags.py
+++ b/python/mlc_llm/interface/compiler_flags.py
@@ -96,7 +96,7 @@ def _flashinfer(target) -> bool:
                 return False
             arch_list = detect_cuda_arch_list(target)
             for arch in arch_list:
-                if int(re.findall(r"\d+", arch)[0]) < 80:
+                if arch < 80:
                     logger.warning("flashinfer is not supported on CUDA arch < 80")
                     return False
             return True
diff --git a/python/mlc_llm/support/auto_target.py b/python/mlc_llm/support/auto_target.py
index 3cf49c43ba..d60be66ced 100644
--- a/python/mlc_llm/support/auto_target.py
+++ b/python/mlc_llm/support/auto_target.py
@@ -293,14 +293,19 @@ def build(mod: IRModule, args: "CompileArgs", pipeline=None):
     return build
 
 
-def detect_cuda_arch_list(target: Target) -> List[str]:
+def detect_cuda_arch_list(target: Target) -> List[int]:
     """Detect the CUDA architecture list from the target."""
+    def convert_to_num(arch_str):
+        arch_num_str = ''.join(filter(str.isdigit, arch_str))
+        assert arch_num_str, f"'{arch_str}' does not contain any digits"
+        return int(arch_num_str)
+
     assert target.kind.name == "cuda", f"Expect target to be CUDA, but got {target}"
     if MLC_MULTI_ARCH is not None:
-        multi_arch = [x.strip() for x in MLC_MULTI_ARCH.split(",")]
+        multi_arch = [convert_to_num(x) for x in MLC_MULTI_ARCH.split(",")]
     else:
         assert target.arch.startswith("sm_")
-        multi_arch = [target.arch[3:]]
+        multi_arch = [convert_to_num(target.arch[3:])]
     multi_arch = list(set(multi_arch))
     return multi_arch