diff --git a/src/plugins/e-acsl/tests/runtime/block_valid.c b/src/plugins/e-acsl/tests/runtime/block_valid.c
index 16be7577c1028872881baebb97e579f0d6e47786..fcda2fa54e15112b86b9bebe3dbdf4dcbe008d81 100644
--- a/src/plugins/e-acsl/tests/runtime/block_valid.c
+++ b/src/plugins/e-acsl/tests/runtime/block_valid.c
@@ -45,7 +45,7 @@ int main(int argc, char **argv) {
   *pmin = 'P';
   *pmax = 'L';
 
-  int diff = pmax - pmin;
+  int diff = (uintptr_t)pmax - (uintptr_t)pmin;
   /*@assert \valid(pmin); */
   /*@assert \valid(pmax); */
   /* Access `pmax` through `pmin` */