diff --git a/build/lib/scripts/prune-images b/build/lib/scripts/prune-images
index 1203d2377..d32c14bf5 100755
--- a/build/lib/scripts/prune-images
+++ b/build/lib/scripts/prune-images
@@ -29,10 +29,13 @@ if [ -z "$needed" ]; then
     exit 1
 fi
 
+MARGIN=${MARGIN:-1073741824}
+target=$((needed + MARGIN))
+
 if [ -h /media/startos/config/current.rootfs ] && [ -e /media/startos/config/current.rootfs ]; then
     echo 'Pruning...'
     current="$(readlink -f /media/startos/config/current.rootfs)"
-    while [[ "$(df -B1 --output=avail --sync /media/startos/images | tail -n1)" -lt "$needed" ]]; do
+    while [[ "$(df -B1 --output=avail --sync /media/startos/images | tail -n1)" -lt "$target" ]]; do
         to_prune="$(ls -t1 /media/startos/images/*.rootfs /media/startos/images/*.squashfs 2> /dev/null | grep -v "$current" | tail -n1)"
         if [ -e "$to_prune" ]; then
             echo "  Pruning $to_prune"
diff --git a/core/src/disk/util.rs b/core/src/disk/util.rs
index d832fee5d..b46f8f31a 100644
--- a/core/src/disk/util.rs
+++ b/core/src/disk/util.rs
@@ -259,6 +259,31 @@ pub async fn recovery_info(
     Ok(res)
 }
 
+/// Returns the canonical path of the source device for a given mount point,
+/// or None if the mount point doesn't exist or isn't mounted.
+#[instrument(skip_all)]
+pub async fn get_mount_source(mountpoint: impl AsRef<Path>) -> Result<Option<PathBuf>, Error> {
+    let mounts_content = tokio::fs::read_to_string("/proc/mounts")
+        .await
+        .with_ctx(|_| (crate::ErrorKind::Filesystem, "/proc/mounts"))?;
+
+    let mountpoint = mountpoint.as_ref();
+    for line in mounts_content.lines() {
+        let mut parts = line.split_whitespace();
+        let source = parts.next();
+        let mount = parts.next();
+        if let (Some(source), Some(mount)) = (source, mount) {
+            if Path::new(mount) == mountpoint {
+                // Try to canonicalize the source path
+                if let Ok(canonical) = tokio::fs::canonicalize(source).await {
+                    return Ok(Some(canonical));
+                }
+            }
+        }
+    }
+    Ok(None)
+}
+
 #[instrument(skip_all)]
 pub async fn list(os: &OsPartitionInfo) -> Result<Vec<DiskInfo>, Error> {
     struct DiskIndex {
diff --git a/core/src/os_install/gpt.rs b/core/src/os_install/gpt.rs
index ff17bb620..2862f88dd 100644
--- a/core/src/os_install/gpt.rs
+++ b/core/src/os_install/gpt.rs
@@ -93,14 +93,14 @@ pub async fn partition(
         };
         gpt.add_partition(
             "boot",
-            1024 * 1024 * 1024,
+            2 * 1024 * 1024 * 1024,
             gpt::partition_types::LINUX_FS,
             0,
             None,
         )?;
         gpt.add_partition(
             "root",
-            15 * 1024 * 1024 * 1024,
+            14 * 1024 * 1024 * 1024,
             match crate::ARCH {
                 "x86_64" => gpt::partition_types::LINUX_ROOT_X64,
                 "aarch64" => gpt::partition_types::LINUX_ROOT_ARM_64,
diff --git a/core/src/os_install/mbr.rs b/core/src/os_install/mbr.rs
index ea68b4695..d643cb7ef 100644
--- a/core/src/os_install/mbr.rs
+++ b/core/src/os_install/mbr.rs
@@ -64,8 +64,8 @@ pub async fn partition(
             };
 
         // MBR partition layout:
-        // Partition 1 (boot): starts at 2048, ends at 2099200 (sectors: 2097152 = 1GB)
-        // Partition 2 (root): starts at 2099200, ends at 33556480 (sectors: 31457280 = 15GB)
+        // Partition 1 (boot): starts at 2048, ends at 4196352 (sectors: 4194304 = 2GB)
+        // Partition 2 (root): starts at 4196352, ends at 33556480 (sectors: 29360128 = 14GB)
         // OS partitions end at sector 33556480
         let os_partitions_end_sector: u32 = 33556480;
 
@@ -99,15 +99,15 @@ pub async fn partition(
             sys: 0x0b,
             last_chs: CHS::empty(),
             starting_lba: 2048,
-            sectors: 2099200 - 2048,
+            sectors: 4196352 - 2048,
         };
         mbr[2] = MBRPartitionEntry {
             boot: 0,
             first_chs: CHS::empty(),
             sys: 0x83,
             last_chs: CHS::empty(),
-            starting_lba: 2099200,
-            sectors: 33556480 - 2099200,
+            starting_lba: 4196352,
+            sectors: 33556480 - 4196352,
         };
 
         let data_part = if let Some((starting_lba, part_sectors, path)) = protected_partition_info {
diff --git a/core/src/setup.rs b/core/src/setup.rs
index 5b9770df8..5317e3699 100644
--- a/core/src/setup.rs
+++ b/core/src/setup.rs
@@ -90,13 +90,24 @@ pub fn disk<C: Context>() -> ParentHandler<C> {
     )
 }
 
+const LIVE_MEDIUM_PATH: &str = "/run/live/medium";
+
 pub async fn list_disks(ctx: SetupContext) -> Result<Vec<DiskInfo>, Error> {
-    crate::disk::util::list(
+    let mut disks = crate::disk::util::list(
         &ctx.config
             .peek(|c| c.os_partitions.clone())
             .unwrap_or_default(),
     )
-    .await
+    .await?;
+
+    // Filter out the disk containing the live medium (installer USB)
+    if let Ok(Some(live_medium_source)) =
+        crate::disk::util::get_mount_source(LIVE_MEDIUM_PATH).await
+    {
+        disks.retain(|disk| disk.logicalname != live_medium_source);
+    }
+
+    Ok(disks)
 }
 
 #[instrument(skip_all)]