diff --git a/src/add-ons/kernel/partitioning_systems/amiga/amiga_rdb.cpp b/src/add-ons/kernel/partitioning_systems/amiga/amiga_rdb.cpp
index 00bda2cd5f..bff002c785 100644
--- a/src/add-ons/kernel/partitioning_systems/amiga/amiga_rdb.cpp
+++ b/src/add-ons/kernel/partitioning_systems/amiga/amiga_rdb.cpp
@@ -180,8 +180,7 @@ amiga_rdb_scan_partition(int fd, partition_data *partition, void *_cookie)
 		disk_environment &environment = *(disk_environment *)&partitionBlock.environment[0];
 		TRACE(("amiga_rdb: file system: %s\n", get_tupel(B_BENDIAN_TO_HOST_INT32(environment.dos_type))));
 
-		if ((uint64)partition->offset + environment.Start()
-			+ environment.Size() > (uint64)partition->size) {
+		if (environment.Start() + environment.Size() > (uint64)partition->size) {
 			TRACE(("amiga_rdb: child partition exceeds existing space (%Ld bytes)\n", environment.Size()));
 			continue;
 		}
diff --git a/src/add-ons/kernel/partitioning_systems/apple/apple.cpp b/src/add-ons/kernel/partitioning_systems/apple/apple.cpp
index cf11978a7f..5562411cd4 100644
--- a/src/add-ons/kernel/partitioning_systems/apple/apple.cpp
+++ b/src/add-ons/kernel/partitioning_systems/apple/apple.cpp
@@ -157,8 +157,7 @@ apple_scan_partition(int fd, partition_data *partition, void *_cookie)
 		TRACE(("apple: found partition: name = \"%s\", type = \"%s\"\n",
 			partitionMap.name, partitionMap.type));
 
-		if ((uint64)partition->offset + partitionMap.Start(descriptor)
-			+ partitionMap.Size(descriptor) > (uint64)partition->size) {
+		if (partitionMap.Start(descriptor) + partitionMap.Size(descriptor) > (uint64)partition->size) {
 			TRACE(("apple: child partition exceeds existing space (%Ld bytes)\n",
 				partitionMap.Size(descriptor)));
 			continue;