diff --git a/checkbox-ng/plainbox/impl/session/resume.py b/checkbox-ng/plainbox/impl/session/resume.py
index db0db7ab81..e052e558bb 100644
--- a/checkbox-ng/plainbox/impl/session/resume.py
+++ b/checkbox-ng/plainbox/impl/session/resume.py
@@ -1082,7 +1082,13 @@ def _rewrite_pathname(cls, pathname, location):
     def _build_IOLogRecord(cls, record_repr):
         """Convert the representation of IOLogRecord back the object."""
         _validate(record_repr, value_type=list)
-        delay = _validate(record_repr, key=0, value_type=float)
+        delay = _validate(record_repr, key=0)
+        try:
+            delay = float(delay)
+        except ValueError:
+            raise CorruptedSessionError(
+                "IOLogRecord has invalid delay {}".format(delay)
+            )
         if delay < 0:
             # TRANSLATORS: please keep delay untranslated
             raise CorruptedSessionError(_("delay cannot be negative"))
diff --git a/checkbox-ng/plainbox/impl/session/test_resume.py b/checkbox-ng/plainbox/impl/session/test_resume.py
index f5289d7f76..9e59826291 100644
--- a/checkbox-ng/plainbox/impl/session/test_resume.py
+++ b/checkbox-ng/plainbox/impl/session/test_resume.py
@@ -812,7 +812,9 @@ def test_build_IOLogRecord_bad_type_for_delay(self):
         verify that _build_IOLogRecord() checks that ``delay`` is float
         """
         with self.assertRaises(CorruptedSessionError):
-            self.parameters.resume_cls._build_IOLogRecord([0, "stdout", ""])
+            self.parameters.resume_cls._build_IOLogRecord(
+                ["abc", "stdout", ""]
+            )
 
     def test_build_IOLogRecord_negative_delay(self):
         """