diff --git a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
index a28b55f8c0..5ae0e5a14e 100644
--- a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
+++ b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.cpp
@@ -399,7 +399,7 @@ Partition::CheckLocation(off_t sessionSize) const
 }
 
 
-void
+bool
 Partition::FitSizeToSession(off_t sessionSize)
 {
 	// To work around buggy (or older) BIOS, we shrink the partition size to
@@ -408,8 +408,12 @@ Partition::FitSizeToSession(off_t sessionSize)
 	// Also, the drive size is obviously reported differently sometimes; this
 	// should let us read problematic drives - let the file system figure out
 	// if something is wrong.
-	if (sessionSize < fOffset + fSize && sessionSize > fOffset)
+	if (sessionSize < fOffset + fSize && sessionSize > fOffset) {
 		fSize = sessionSize - fOffset;
+		return true;
+	}
+
+	return false;
 }
 
 
diff --git a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.h b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.h
index c35fa2fa0f..647e10c6be 100644
--- a/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.h
+++ b/src/add-ons/kernel/partitioning_systems/intel/PartitionMap.h
@@ -182,7 +182,7 @@ public:
 									{ fBlockSize = blockSize; }
 
 			bool				CheckLocation(off_t sessionSize) const;
-			void				FitSizeToSession(off_t sessionSize);
+			bool				FitSizeToSession(off_t sessionSize);
 
 private:
 			off_t				fPartitionTableOffset;
diff --git a/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.cpp b/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.cpp
index a758d2a59b..e94b0201cb 100644
--- a/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.cpp
+++ b/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.cpp
@@ -67,18 +67,45 @@ PartitionMapParser::Parse(const uint8* block, PartitionMap* map)
 		return B_BAD_VALUE;
 
 	status_t error;
+	bool hadToReFitSize = false;
 
 	fMap = map;
 	fMap->Unset();
 
 	if (block) {
 		const partition_table* table = (const partition_table*)block;
-		error = _ParsePrimary(table);
+		error = _ParsePrimary(table, hadToReFitSize);
 	} else {
 		partition_table table;
 		error = _ReadPartitionTable(0, &table);
-		if (error == B_OK)
-			error = _ParsePrimary(&table);
+		if (error == B_OK) {
+			error = _ParsePrimary(&table, hadToReFitSize);
+
+			if (fBlockSize != 512 && (hadToReFitSize
+					|| !fMap->Check(fSessionSize))) {
+				// This might be a fixed 512 byte MBR on a non-512 medium.
+				// We do that for the anyboot images for example. so retry
+				// with a fixed 512 block size and see if we get better
+				// results
+				int32 previousPartitionCount = fMap->CountNonEmptyPartitions();
+				uint32 previousBlockSize = fBlockSize;
+				TRACE(("intel: Parse(): trying with a fixed 512 block size\n"));
+
+				fBlockSize = 512;
+				fMap->Unset();
+				error = _ParsePrimary(&table, hadToReFitSize);
+
+				if (fMap->CountNonEmptyPartitions() < previousPartitionCount
+					|| error != B_OK || hadToReFitSize
+					|| !fMap->Check(fSessionSize)) {
+					// That didn't improve anything, let's revert.
+					TRACE(("intel: Parse(): try failed, reverting\n"));
+					fBlockSize = previousBlockSize;
+					fMap->Unset();
+					error = _ParsePrimary(&table, hadToReFitSize);
+				}
+			}
+		}
 	}
 
 	if (error == B_OK && !fMap->Check(fSessionSize))
@@ -92,7 +119,8 @@ PartitionMapParser::Parse(const uint8* block, PartitionMap* map)
 
 // _ParsePrimary
 status_t
-PartitionMapParser::_ParsePrimary(const partition_table* table)
+PartitionMapParser::_ParsePrimary(const partition_table* table,
+	bool& hadToReFitSize)
 {
 	if (table == NULL)
 		return B_BAD_VALUE;
@@ -104,6 +132,8 @@ PartitionMapParser::_ParsePrimary(const partition_table* table)
 		return B_BAD_DATA;
 	}
 
+	hadToReFitSize = false;
+
 	// examine the table
 	for (int32 i = 0; i < 4; i++) {
 		const partition_descriptor* descriptor = &table->table[i];
@@ -111,7 +141,7 @@ PartitionMapParser::_ParsePrimary(const partition_table* table)
 		partition->SetTo(descriptor, 0, fBlockSize);
 
 		// work-around potential BIOS/OS problems
-		partition->FitSizeToSession(fSessionSize);
+		hadToReFitSize |= partition->FitSizeToSession(fSessionSize);
 
 		// ignore, if location is bad
 		if (!partition->CheckLocation(fSessionSize)) {
diff --git a/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.h b/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.h
index 4ecf85b92f..7034bacdd9 100644
--- a/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.h
+++ b/src/add-ons/kernel/partitioning_systems/intel/PartitionMapParser.h
@@ -38,7 +38,8 @@ public:
 			const Partition*	PartitionAt(int32 index) const;
 
 private:
-			status_t			_ParsePrimary(const partition_table* table);
+			status_t			_ParsePrimary(const partition_table* table,
+									bool& hadToReFitSize);
 			status_t			_ParseExtended(PrimaryPartition* primary,
 									off_t offset);
 			status_t			_ReadPartitionTable(off_t offset,