diff --git a/pystencils_benchmark/common.py b/pystencils_benchmark/common.py
index beeeed69cf7225dc91ad45cb8ad833ca1cdf10e7..70cabd6dbe329b0a92c6a906dff6b262698508da 100644
--- a/pystencils_benchmark/common.py
+++ b/pystencils_benchmark/common.py
@@ -16,15 +16,17 @@ def _kernel_header(kernel_ast: KernelFunction,
                    dialect: Backend = Backend.C,
                    *,
                    template_file: str,
-                   additional_jinja_context: dict = {}) -> str:
+                   additional_jinja_context: dict = None) -> str:
+
     function_signature = generate_c(kernel_ast, dialect=dialect, signature_only=True)
     header_guard = f'_{kernel_ast.function_name.upper()}_H'
 
     jinja_context = {
         'header_guard': header_guard,
         'function_signature': function_signature,
-        **additional_jinja_context
     }
+    if additional_jinja_context is not None:
+        jinja_context.update(additional_jinja_context)
 
     header = _env.get_template(template_file).render(**jinja_context)
     return header
@@ -34,7 +36,8 @@ def _kernel_source(kernel_ast: KernelFunction,
                    dialect: Backend = Backend.C,
                    *,
                    template_file: str,
-                   additional_jinja_context: dict = {}) -> str:
+                   additional_jinja_context: dict = None) -> str:
+
     kernel_name = kernel_ast.function_name
     function_source = generate_c(kernel_ast, dialect=dialect)
     headers = {f'"{kernel_name}.h"', '<math.h>', '<stdint.h>'}
@@ -44,9 +47,11 @@ def _kernel_source(kernel_ast: KernelFunction,
         'function_source': function_source,
         'headers': sorted(headers),
         'timing': True,
-        **additional_jinja_context,
     }
 
+    if additional_jinja_context is not None:
+        jinja_context.update(additional_jinja_context)
+
     source = _env.get_template(template_file).render(**jinja_context)
     return source