diff --git a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
index 1467c52dcc..96a5a38308 100644
--- a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
+++ b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
@@ -220,7 +220,7 @@ Partition::AdjustSize(off_t sessionSize)
 	// To work around buggy (or older) BIOS, we shrink the partition size to
 	// always fit into its session - this should improve detection of boot
 	// partitions (see bug #238 for more information)
-	if (sessionSize < fOffset + fSize)
+	if (sessionSize < fOffset + fSize && sessionSize > fOffset)
 		fSize = sessionSize - fOffset;
 }
 #endif