diff --git a/src/plugins/e-acsl/share/e-acsl/observation_model/e_acsl_observation_model.h b/src/plugins/e-acsl/share/e-acsl/observation_model/e_acsl_observation_model.h
index 4a5a8204afda7fc9457a9b68a8c7712c5290ee09..12ce416be2984b2edce0a5080c8df258ca0ac9b2 100644
--- a/src/plugins/e-acsl/share/e-acsl/observation_model/e_acsl_observation_model.h
+++ b/src/plugins/e-acsl/share/e-acsl/observation_model/e_acsl_observation_model.h
@@ -36,6 +36,9 @@
 #include "../internals/e_acsl_alias.h"
 #include "e_acsl_heap.h"
 
+#ifdef __FC_STDLIB
+#include <__fc_alloc_axiomatic.h>
+#else
 /*@ ghost extern int __fc_heap_status; */
 
 /*@ axiomatic dynamic_allocation {
@@ -45,9 +48,10 @@
   @   // predicate depends on the memory state
   @   axiom never_allocable{L}:
   @     \forall integer i;
-  @        i < 0 || i > __FC_SIZE_MAX ==> !is_allocable(i);
+  @        i < 0 || i > SIZE_MAX ==> !is_allocable(i);
   @ }
 */
+#endif
 
 /************************************************************************/
 /*** API Prefixes {{{ ***/