diff --git a/kernel_tuner/interface.py b/kernel_tuner/interface.py
index 97ae2284..bd421aea 100644
--- a/kernel_tuner/interface.py
+++ b/kernel_tuner/interface.py
@@ -592,8 +592,8 @@ def tune_kernel(
     # check for forbidden names in tune parameters
     util.check_tune_params_list(tune_params, observers, simulation_mode=simulation_mode)
 
-    # check whether block_size_names are used as expected
-    util.check_block_size_params_names_list(block_size_names, tune_params)
+    # check whether block_size_names are used
+    block_size_names = util.check_block_size_params_names_list(block_size_names, tune_params)
 
     # ensure there is always at least three names
     util.append_default_block_size_names(block_size_names)
diff --git a/kernel_tuner/util.py b/kernel_tuner/util.py
index 0d2cef69..52279dcb 100644
--- a/kernel_tuner/util.py
+++ b/kernel_tuner/util.py
@@ -237,11 +237,22 @@ def check_block_size_params_names_list(block_size_names, tune_params):
                     "Block size name " + name + " is not specified in the tunable parameters list!", UserWarning
                 )
     else:  # if default block size names are used
-        if not any([k in default_block_size_names for k in tune_params.keys()]):
+        if not any([k.lower() in default_block_size_names for k in tune_params.keys()]):
             warnings.warn(
                 "None of the tunable parameters specify thread block dimensions!",
                 UserWarning,
             )
+        else:
+            # check for alternative case spelling of defaults such as BLOCK_SIZE_X or block_Size_X etc
+            result = []
+            for k in tune_params.keys():
+                if k.lower() in default_block_size_names and k not in default_block_size_names:
+                    result.append(k)
+            # ensure order of block_size_names is correct regardless of case used
+            block_size_names = sorted(result, key=str.casefold)
+
+    return block_size_names
+
 
 def check_restriction(restrict, params: dict) -> bool:
     """Check whether a configuration meets a search space restriction."""