diff --git a/fastboot/fastboot.cpp b/fastboot/fastboot.cpp
index 080ad42..63f7843 100644
--- a/fastboot/fastboot.cpp
+++ b/fastboot/fastboot.cpp
@@ -1413,12 +1413,19 @@
     }
 }
 
-bool is_retrofit_device(fastboot::IFastBootDriver* fb) {
-    std::string value;
-    if (fb->GetVar("super-partition-name", &value) != fastboot::SUCCESS) {
+bool is_retrofit_device(const ImageSource* source) {
+    // Does this device use dynamic partitions at all?
+    std::vector<char> contents;
+    if (!source->ReadFile("super_empty.img", &contents)) {
         return false;
     }
-    return android::base::StartsWith(value, "system_");
+    auto metadata = android::fs_mgr::ReadFromImageBlob(contents.data(), contents.size());
+    for (const auto& partition : metadata->partitions) {
+        if (partition.attributes & LP_PARTITION_ATTR_SLOT_SUFFIXED) {
+            return true;
+        }
+    }
+    return false;
 }
 
 // Fetch a partition from the device to a given fd. This is a wrapper over FetchToFd to fetch
@@ -1876,7 +1883,7 @@
         // On these devices, secondary slots must be flashed as physical
         // partitions (otherwise they would not mount on first boot). To enforce
         // this, we delete any logical partitions for the "other" slot.
-        if (is_retrofit_device(fp_->fb)) {
+        if (is_retrofit_device(fp_->source)) {
             std::string partition_name = image->part_name + "_" + slot;
             if (image->IsSecondary() && should_flash_in_userspace(partition_name)) {
                 tasks.emplace_back(std::make_unique<DeleteTask>(fp_, partition_name));
diff --git a/fastboot/fastboot.h b/fastboot/fastboot.h
index 35deea7..eead82c 100644
--- a/fastboot/fastboot.h
+++ b/fastboot/fastboot.h
@@ -187,7 +187,7 @@
 std::vector<SparsePtr> resparse_file(sparse_file* s, int64_t max_size);
 
 bool supports_AB(fastboot::IFastBootDriver* fb);
-bool is_retrofit_device(fastboot::IFastBootDriver* fb);
+bool is_retrofit_device(const ImageSource* source);
 bool is_logical(const std::string& partition);
 void fb_perform_format(const std::string& partition, int skip_if_not_supported,
                        const std::string& type_override, const std::string& size_override,