diff --git a/src/plugins/value/Eva.mli b/src/plugins/value/Eva.mli
index bad7b93a157c584374215a7fffb32031286a1d5f..07f108a1bb76bb262fcae36da22eb3c6f78923a2 100644
--- a/src/plugins/value/Eva.mli
+++ b/src/plugins/value/Eva.mli
@@ -139,7 +139,11 @@ module Results: sig
 
   (** Working with callstacks *)
 
-  (** Returns the list of reachable callstacks from the given request. *)
+  (** Returns the list of reachable callstacks from the given request.
+      An empty list is returned if the request control point has not been
+      reached by the analysis, or if no information has been saved at this point
+      (for instance with the -eva-no-results option).
+      Use [is_empty request] to distinguish these two cases. *)
   val callstacks : request -> callstack list
 
   (** Returns a list of subrequests for each reachable callstack from
diff --git a/src/plugins/value/utils/results.mli b/src/plugins/value/utils/results.mli
index 2bba4a21ee693cb5e2810edd631f0196ca3f960f..37f7bf897162748e443f4dd82ddd5e74c777b1e2 100644
--- a/src/plugins/value/utils/results.mli
+++ b/src/plugins/value/utils/results.mli
@@ -127,7 +127,11 @@ val filter_callstack : (callstack -> bool) -> request -> request
 
 (** Working with callstacks *)
 
-(** Returns the list of reachable callstacks from the given request. *)
+(** Returns the list of reachable callstacks from the given request.
+    An empty list is returned if the request control point has not been
+    reached by the analysis, or if no information has been saved at this point
+    (for instance with the -eva-no-results option).
+    Use [is_empty request] to distinguish these two cases. *)
 val callstacks : request -> callstack list
 
 (** Returns a list of subrequests for each reachable callstack from