diff --git a/src/defer_imports/_core.py b/src/defer_imports/_core.py
index 6008dea..4b53e76 100644
--- a/src/defer_imports/_core.py
+++ b/src/defer_imports/_core.py
@@ -320,15 +320,6 @@ def check_ast_for_defer_usage(data: ast.AST) -> tuple[str, bool]:
 class DeferredFileLoader(SourceFileLoader):
     """A file loader that instruments .py files which use "with defer_imports.until_use: ..."."""
 
-    @staticmethod
-    def check_for_defer_usage(data: SourceData) -> tuple[str, bool]:
-        """Check if the given data uses "with defer_imports.until_use"."""
-
-        if isinstance(data, ast.AST):
-            return check_ast_for_defer_usage(data)
-        else:
-            return check_source_for_defer_usage(data)
-
     def source_to_code(  # pyright: ignore [reportIncompatibleMethodOverride]
         self,
         data: SourceData,
@@ -342,12 +333,16 @@ def source_to_code(  # pyright: ignore [reportIncompatibleMethodOverride]
         if not data:
             return super().source_to_code(data, path, _optimize=_optimize)  # pyright: ignore # See note above.
 
-        encoding, uses_defer = self.check_for_defer_usage(data)
+        # Check if the given data uses "with defer_imports.until_use".
+        if isinstance(data, ast.AST):
+            encoding, uses_defer = check_ast_for_defer_usage(data)
+        else:
+            encoding, uses_defer = check_source_for_defer_usage(data)
 
         if not uses_defer:
             return super().source_to_code(data, path, _optimize=_optimize)  # pyright: ignore # See note above.
 
-        # Get the AST of the given data, instrument it, and fix missing line and column numbers.
+        # Instrument the AST of the given data.
         transformer = DeferredInstrumenter(data, path, encoding)
 
         if isinstance(data, ast.AST):
diff --git a/src/defer_imports/console.py b/src/defer_imports/console.py
index 5a573f7..201400f 100644
--- a/src/defer_imports/console.py
+++ b/src/defer_imports/console.py
@@ -74,7 +74,7 @@ def __init__(self):
         self.actual_transformer = DeferredInstrumenter("", "<unknown>", "utf-8")
 
     def visit(self, node: ast.AST) -> _tp.Any:
-        # Reset part of the wrapped transformer before use.
+        # Reset part of the wrapped transformer before (re)use.
         self.actual_transformer.data = node
         self.actual_transformer.scope_depth = 0
         return ast.fix_missing_locations(self.actual_transformer.visit(node))
@@ -84,12 +84,17 @@ def instrument_ipython() -> None:
     """Add defer_import's compile-time AST transformer to a currently running IPython environment.
 
     This will ensure that defer_imports.until_use works as intended when used directly in a IPython console.
+
+    Raises
+    ------
+    RuntimeError
+        If called in a non-IPython environment.
     """
 
     try:
         ipython_shell: _tp.Any = get_ipython()  # pyright: ignore
     except NameError:
-        msg = "Not currently in an IPython/Jupyter environment."
+        msg = "Not currently in an IPython environment."
         raise RuntimeError(msg) from None
 
     ipython_shell.ast_transformers.append(_DeferredIPythonInstrumenter())