diff --git a/src/modules/fstab/main.py b/src/modules/fstab/main.py
index 4a696f46b..c58e8eb11 100644
--- a/src/modules/fstab/main.py
+++ b/src/modules/fstab/main.py
@@ -218,7 +218,6 @@ class FstabGenerator(object):
 
                 else:
                     dct = self.generate_fstab_line_info(partition)
-
                     if dct:
                         self.print_fstab_line(dct, file=fstab_file)
 
@@ -233,19 +232,30 @@ class FstabGenerator(object):
                 self.print_fstab_line(dct, file=fstab_file)
 
     def generate_fstab_line_info(self, partition):
-        """ Generates information for each fstab entry. """
+        """
+        Generates information (a dictionary of fstab-fields)
+        for the given @p partition.
+        """
+        # Some "fs" names need special handling in /etc/fstab, so remap them.
         filesystem = partition["fs"].lower()
+        filesystem = FS_MAP.get(filesystem, filesystem)
         has_luks = "luksMapperName" in partition
         mount_point = partition["mountPoint"]
         disk_name = disk_name_for_partition(partition)
         is_ssd = disk_name in self.ssd_disks
-        filesystem = FS_MAP.get(filesystem, filesystem)
 
+        # Swap partitions are called "linuxswap" by parted.
+        # That "fs" is visible in GS, but that gets mapped
+        # to "swap", above, because that's the spelling needed in /etc/fstab
         if not mount_point and not filesystem == "swap":
             return None
         if not mount_point:
             mount_point = "swap"
 
+        if filesystem == "swap" and not partition.get("claimed", None):
+            libcalamares.utils.debug("Ignoring foreign swap {!s} {!s}".format(disk_name, partition.get("uuid", None)))
+            return None
+
         options = self.get_mount_options(filesystem, mount_point)
 
         if is_ssd:
diff --git a/src/modules/grubcfg/main.py b/src/modules/grubcfg/main.py
index 5d9428eeb..0df255e75 100644
--- a/src/modules/grubcfg/main.py
+++ b/src/modules/grubcfg/main.py
@@ -80,6 +80,9 @@ def modify_grub_default(partitions, root_mount_point, distributor):
 
     if have_dracut:
         for partition in partitions:
+            if partition["fs"] == "linuxswap" and not partition.get("claimed", None):
+                # Skip foreign swap
+                continue
             has_luks = "luksMapperName" in partition
             if partition["fs"] == "linuxswap" and not has_luks:
                 swap_uuid = partition["uuid"]
@@ -94,6 +97,9 @@ def modify_grub_default(partitions, root_mount_point, distributor):
                     ]
     else:
         for partition in partitions:
+            if partition["fs"] == "linuxswap" and not partition.get("claimed", None):
+                # Skip foreign swap
+                continue
             has_luks = "luksMapperName" in partition
             if partition["fs"] == "linuxswap" and not has_luks:
                 swap_uuid = partition["uuid"]
diff --git a/src/modules/partition/core/PartitionCoreModule.h b/src/modules/partition/core/PartitionCoreModule.h
index 7faf67863..38a52249f 100644
--- a/src/modules/partition/core/PartitionCoreModule.h
+++ b/src/modules/partition/core/PartitionCoreModule.h
@@ -224,10 +224,10 @@ public:
      */
     QList< SummaryInfo > createSummaryInfo() const;
 
-    void dumpQueue() const; // debug output
-
     const OsproberEntryList osproberEntries() const;    // os-prober data structure, cached
 
+    void dumpQueue() const; // debug output
+
 Q_SIGNALS:
     void hasRootMountPointChanged( bool value );
     void isDirtyChanged( bool value );
diff --git a/src/modules/partition/jobs/FillGlobalStorageJob.cpp b/src/modules/partition/jobs/FillGlobalStorageJob.cpp
index 12faaf969..c909ba913 100644
--- a/src/modules/partition/jobs/FillGlobalStorageJob.cpp
+++ b/src/modules/partition/jobs/FillGlobalStorageJob.cpp
@@ -100,14 +100,18 @@ mapForPartition( Partition* partition, const QString& uuid )
         map[ "fs" ] = untranslatedFS( dynamic_cast< FS::luks& >( partition->fileSystem() ).innerFS() );
     }
     map[ "uuid" ] = uuid;
+    map[ "claimed" ] = PartitionInfo::format( partition );  // If we formatted it, it's ours
 
     // Debugging for inside the loop in createPartitionList(),
     // so indent a bit
     Logger::CDebug deb;
     using TR = Logger::DebugRow< const char* const, const QString& >;
     deb << Logger::SubEntry << "mapping for" << partition->partitionPath() << partition->deviceNode()
-        << TR( "mtpoint:", PartitionInfo::mountPoint( partition ) ) << TR( "fs:", map[ "fs" ].toString() )
-        << TR( "fsName", map[ "fsName" ].toString() ) << TR( "uuid", uuid );
+        << TR( "mtpoint:", PartitionInfo::mountPoint( partition ) )
+        << TR( "fs:", map[ "fs" ].toString() )
+        << TR( "fsName", map[ "fsName" ].toString() )
+        << TR( "uuid", uuid )
+        << TR( "claimed", map[ "claimed" ].toString() );
 
     if ( partition->roles().has( PartitionRole::Luks ) )
     {
@@ -213,6 +217,7 @@ FillGlobalStorageJob::exec()
 {
     Calamares::GlobalStorage* storage = Calamares::JobQueue::instance()->globalStorage();
     storage->insert( "partitions", createPartitionList() );
+    cDebug() << "Saving partition information map to GlobalStorage[\"partitions\"]";
     if ( !m_bootLoaderPath.isEmpty() )
     {
         QVariant var = createBootLoaderMap();
@@ -236,7 +241,7 @@ FillGlobalStorageJob::createPartitionList() const
 {
     UuidForPartitionHash hash = findPartitionUuids( m_devices );
     QVariantList lst;
-    cDebug() << "Writing to GlobalStorage[\"partitions\"]";
+    cDebug() << "Building partition information map";
     for ( auto device : m_devices )
     {
         cDebug() << Logger::SubEntry << "partitions on" << device->deviceNode();