diff --git a/guardrails/prompt/base_prompt.py b/guardrails/prompt/base_prompt.py
index 643313eff..06b4a3a3e 100644
--- a/guardrails/prompt/base_prompt.py
+++ b/guardrails/prompt/base_prompt.py
@@ -6,7 +6,6 @@
 
 import regex
 
-from guardrails.namespace_template import NamespaceTemplate
 from guardrails.utils.constants import constants
 from guardrails.utils.parsing_utils import get_template_variables
 
@@ -17,8 +16,13 @@ class BasePrompt:
     def __init__(self, source: str, output_schema: Optional[str] = None):
         self.format_instructions_start = self.get_format_instructions_idx(source)
 
-        # Substitute constants in the prompt.
-        source = self.substitute_constants(source)
+        # Warn if the prompt uses the old constant schema.
+        if self.uses_old_constant_schema(source):
+            warnings.warn(
+                "You may be using an an unsupported convention for specifying "
+                "guardrails variables. Follow the new namespaced convention "
+                "documented here: https://docs.guardrailsai.com/0-2-migration/"
+            )
 
         # If an output schema is provided, substitute it in the prompt.
         if output_schema:
@@ -44,28 +48,6 @@ def variable_names(self):
     def format_instructions(self):
         return self.source[self.format_instructions_start :]
 
-    def substitute_constants(self, text):
-        """Substitute constants in the prompt."""
-        # Substitute constants by reading the constants file.
-        # Regex to extract all occurrences of ${gr.<constant_name>}
-        if self.uses_old_constant_schema(text):
-            warnings.warn(
-                "It appears that you are using an old schema for gaurdrails variables, "
-                "follow the new namespaced convention "
-                "documented here: https://docs.guardrailsai.com/0-2-migration/"
-            )
-
-        matches = re.findall(r"\${gr\.(\w+)}", text)
-
-        # Substitute all occurrences of ${gr.<constant_name>}
-        #   with the value of the constant.
-        for match in matches:
-            template = NamespaceTemplate(text)
-            mapping = {f"gr.{match}": constants[match]}
-            text = template.safe_substitute(**mapping)
-
-        return text
-
     def uses_old_constant_schema(self, text) -> bool:
         matches = re.findall(r"@(\w+)", text)
         if len(matches) == 0: