diff --git a/src/linux/py_proc.h b/src/linux/py_proc.h
index 2ceaf67..3dd460f 100644
--- a/src/linux/py_proc.h
+++ b/src/linux/py_proc.h
@@ -402,7 +402,6 @@ _py_proc__parse_maps_file(py_proc_t * self) {
       size_t page_size = getpagesize();
       map->bss_base = (void *) lower - page_size;
       map->bss_size = upper - lower + page_size;
-      maps_flag |= BSS_MAP;
       log_d("Inferred BSS for %s: %lx-%lx", map->path, lower, upper);
     }
 
@@ -539,10 +538,22 @@ _py_proc__parse_maps_file(py_proc_t * self) {
   self->map.bss.base = pd->maps[map_index].bss_base;
   self->map.bss.size = pd->maps[map_index].bss_size;
   
+  if (!isvalid(self->map.bss.base)) {
+    log_e("Cannot find valid BSS map");
+    set_error(EPROCVM);
+    FAIL;
+  }
+
+  if (!(maps_flag & (BIN_MAP))) {
+    log_e("No usable Python binary found");
+    set_error(EPROC);
+    FAIL;
+  }
+
   log_d("BSS map %d from %s @ %p", map_index, pd->maps[map_index].path, self->map.bss.base);
   log_d("VM maps parsing result: bin=%s lib=%s flags=%d", self->bin_path, self->lib_path, maps_flag);
 
-  return !(maps_flag & (BIN_MAP | BSS_MAP));
+  SUCCESS;
 } /* _py_proc__parse_maps_file */
 
 
diff --git a/test/test_attach.py b/test/test_attach.py
index 03e1eb2..9a17cbc 100644
--- a/test/test_attach.py
+++ b/test/test_attach.py
@@ -50,8 +50,8 @@
 @allpythons()
 @variants
 def test_attach_wall_time(austin, py, mode, mode_meta, heap):
-    with run_python(py, target("sleepy.py"), "1") as p:
-        sleep(0.4)
+    with run_python(py, target("sleepy.py"), "2") as p:
+        sleep(0.5)
 
         result = austin(mode, "2ms", *heap, "-p", str(p.pid))
         assert result.returncode == 0
@@ -189,4 +189,4 @@ def test_attach_container_like(py, tmp_path, prefix):
         a = sum_metric(result.stdout)
         d = int(meta["duration"])
 
-        assert abs(a - d) <= (a + d) * 0.1
+        assert abs(a - d) <= (a + d) * 0.25
diff --git a/test/test_valgrind.py b/test/test_valgrind.py
index 9582086..2e46547 100644
--- a/test/test_valgrind.py
+++ b/test/test_valgrind.py
@@ -67,7 +67,7 @@ def test_valgrind_fork(py, mode):
 @pytest.mark.parametrize("mode", ["", "s", "C", "Cs"])
 @allpythons()
 def test_valgrind_attach(py, mode):
-    with run_python(py, target("sleepy.py")) as p:
+    with run_python(py, target("sleepy.py"), "2") as p:
         result = valgrind(["-p", str(p.pid)], mode)
         assert result.returncode == 0, "\n".join((result.stdout, result.stderr))
         p.kill()