diff --git a/gptel-org.el b/gptel-org.el
index eceb491c..7df20121 100644
--- a/gptel-org.el
+++ b/gptel-org.el
@@ -158,9 +158,12 @@ value of `gptel-org-branching-context', which see."
   (let ((max-entries (and gptel--num-messages-to-send
                           (* 2 gptel--num-messages-to-send)))
         (topic-start (gptel-org--get-topic-start)))
-    (when topic-start
-      ;; narrow to GPTEL_TOPIC property scope
-      (narrow-to-region topic-start prompt-end))
+    (if topic-start
+        ;; narrow to GPTEL_TOPIC property scope
+        (narrow-to-region topic-start prompt-end)
+      (when (and gptel-force-prompt-context-be-explicit (buffer-file-name))
+        (error "explicit prompt context forced but org's topic not present
+ along hierarchical lineage of the current Org heading")))
     (if gptel-org-branching-context
         ;; Create prompt from direct ancestors of point
         (if (fboundp 'org-element-lineage-map)
@@ -203,6 +206,8 @@ value of `gptel-org-branching-context', which see."
              '(gptel org)
              "Using `gptel-org-branching-context' requires Org version 9.6.7 or higher, it will be ignored.")
           (gptel--parse-buffer gptel-backend max-entries))
+      (when (and gptel-force-prompt-context-be-explicit (buffer-file-name))
+        (error "explicit prompt context forced but org's branching context is not set"))
       ;; Create prompt the usual way
       (gptel--parse-buffer gptel-backend max-entries))))
 
diff --git a/gptel.el b/gptel.el
index 5f217e0a..c8599a4c 100644
--- a/gptel.el
+++ b/gptel.el
@@ -514,6 +514,19 @@ with `gptel-mode' enabled), where user prompts and responses are
 always handled separately."
   :type 'boolean)
 
+(defcustom gptel-force-prompt-context-be-explicit nil
+  "Force the context that is sent along the prompt be explicitly bound.
+
+If non-nil, then:
+For Org mode's FILE buffers: `gptel-org-branching-context' must be non-nil
+                              and conversation topic needs to be present
+                              in hierarchical lineage of the current Org
+                              heading.
+For other buffers: region must be marked."
+  :local t
+  :type 'boolean
+  :group 'gptel)
+
 (defvar-local gptel--old-header-line nil)
 
 
@@ -1050,8 +1063,11 @@ there."
          ((derived-mode-p 'org-mode)
           (require 'gptel-org)
           (gptel-org--create-prompt (or prompt-end (point-max))))
-         (t (goto-char (or prompt-end (point-max)))
-            (gptel--parse-buffer gptel-backend max-entries)))))))
+         (t
+          (when gptel-force-prompt-context-be-explicit
+            (error "explicit prompt context forced but region is NOT marked"))
+          (goto-char (or prompt-end (point-max)))
+          (gptel--parse-buffer gptel-backend max-entries)))))))
 
 (cl-defgeneric gptel--parse-buffer (backend max-entries)
   "Parse current buffer backwards from point and return a list of prompts.