diff --git a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
index 5ae0e5a14e..8a4e70a297 100644
--- a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
+++ b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
@@ -361,6 +361,8 @@ Partition::Unset()
 bool
 Partition::CheckLocation(off_t sessionSize) const
 {
+	if (fBlockSize == 0)
+			return false;
 	// offsets and size must be block aligned, partition table and partition must
 	// lie within the session
 	if (fPartitionTableOffset % fBlockSize != 0) {