diff --git a/docs/ENVIRONMENT.md b/docs/ENVIRONMENT.md
index 3a35c1b9aa..6eda26c7d6 100644
--- a/docs/ENVIRONMENT.md
+++ b/docs/ENVIRONMENT.md
@@ -529,6 +529,15 @@ disk images with `--image=` or similar:
   systems that may be mounted for automatically dissected disk images. If not
   specified defaults to something like: `ext4:btrfs:xfs:vfat:erofs:squashfs`
 
+* `$SYSTEMD_DISSECT_FSTYPE_<DESIGNATOR>=` – overrides the file system time to
+  use when mounting the partition of the indicated designator. The
+  `<DESIGNATOR>` string shall be one of `ROOT`, `USR`, `HOME`, `SRV`, `ESP`,
+  `XBOOTLDR`, `TMP`, `VAR` as per the [Discoverable Partitions
+  Specification](https://uapi-group.org/specifications/specs/discoverable_partitions_specification/). If
+  unspecified the image dissection logic will automatically probe the file
+  system type (subject to `$SYSTEMD_DISSECT_FILE_SYSTEMS`, see above), except
+  for ESP and XBOOTLDR where the file system type is set to VFAT.
+
 * `$SYSTEMD_LOOP_DIRECT_IO` – takes a boolean, which controls whether to enable
   `LO_FLAGS_DIRECT_IO` (i.e. direct IO + asynchronous IO) on loopback block
   devices when opening them. Defaults to on, set this to "0" to disable this
diff --git a/src/shared/dissect-image.c b/src/shared/dissect-image.c
index e44c307bbf..4cb84116fa 100644
--- a/src/shared/dissect-image.c
+++ b/src/shared/dissect-image.c
@@ -117,6 +117,17 @@ int dissect_fstype_ok(const char *fstype) {
         return false;
 }
 
+static const char *getenv_fstype(PartitionDesignator d) {
+
+        if (d < 0 ||
+            partition_designator_is_verity(d) ||
+            d == PARTITION_SWAP)
+                return NULL;
+
+        char *v = strjoina("SYSTEMD_DISSECT_FSTYPE_", partition_designator_to_string(d));
+        return secure_getenv(ascii_strupper(v));
+}
+
 int probe_sector_size(int fd, uint32_t *ret) {
 
         /* Disk images might be for 512B or for 4096 sector sizes, let's try to auto-detect that by searching
@@ -1032,7 +1043,7 @@ static int dissect_image(
                 }
 
                 if (is_gpt) {
-                        const char *fstype = NULL, *label;
+                        const char *label;
                         sd_id128_t type_id, id;
                         GptPartitionType type;
                         bool rw = true, growfs = false;
@@ -1085,6 +1096,8 @@ static int dissect_image(
                                 continue;
                         }
 
+                        const char *fstype = getenv_fstype(type.designator);
+
                         if (IN_SET(type.designator,
                                    PARTITION_HOME,
                                    PARTITION_SRV,
@@ -1097,6 +1110,11 @@ static int dissect_image(
                                 rw = !(pflags & SD_GPT_FLAG_READ_ONLY);
                                 growfs = FLAGS_SET(pflags, SD_GPT_FLAG_GROWFS);
 
+                                /* XBOOTLDR cannot be integrity protected (since firmware needs to access
+                                 * it), hence be restrictive with the fs choice when dissecting. */
+                                if (type.designator == PARTITION_XBOOTLDR && !fstype)
+                                        fstype = "vfat";
+
                         } else if (type.designator == PARTITION_ESP) {
 
                                 if (FLAGS_SET(pflags, SD_GPT_FLAG_NO_BLOCK_IO_PROTOCOL)) {
@@ -1104,7 +1122,9 @@ static int dissect_image(
                                         continue;
                                 }
 
-                                fstype = "vfat";
+                                /* Effectively the ESP has to be VFAT, let's enforce this */
+                                if (!fstype)
+                                        fstype = "vfat";
 
                         } else if (type.designator == PARTITION_ROOT) {
 
diff --git a/test/units/TEST-87-AUX-UTILS-VM.bootctl.sh b/test/units/TEST-87-AUX-UTILS-VM.bootctl.sh
index c6b4ea0655..c8e3da09cf 100755
--- a/test/units/TEST-87-AUX-UTILS-VM.bootctl.sh
+++ b/test/units/TEST-87-AUX-UTILS-VM.bootctl.sh
@@ -158,6 +158,8 @@ EOF
 
     umount "${IMAGE_DIR}/root"
 
+    export SYSTEMD_DISSECT_FSTYPE_XBOOTLDR=ext4
+
     assert_eq "$(bootctl --image "${IMAGE_DIR}/image" --print-esp-path)" "/run/systemd/mount-rootfs/efi"
     assert_eq "$(bootctl --image "${IMAGE_DIR}/image" --print-esp-path --esp-path=/efi)" "/run/systemd/mount-rootfs/efi"
     assert_eq "$(bootctl --image "${IMAGE_DIR}/image" --print-boot-path)" "/run/systemd/mount-rootfs/boot"
@@ -167,6 +169,8 @@ EOF
     bootctl --image "${IMAGE_DIR}/image" --print-root-device || :
 
     basic_tests --image "${IMAGE_DIR}/image"
+
+    unset SYSTEMD_DISSECT_FSTYPE_XBOOTLDR
 }
 
 cleanup_raid() (