diff --git a/doc/using.md b/doc/using.md
index fd8e0851..85fd4001 100644
--- a/doc/using.md
+++ b/doc/using.md
@@ -267,7 +267,8 @@ FluxEngine also supports a number of file system image formats. When using the
   - `<filename.fdi>`
 
   Read from a [FDI image file](https://www.pc98.org/project/doc/hdi.html),
-  commonly used by PC-98 emulators. **Read Only.**
+  commonly used by PC-98 emulators. Supports automatically configuring
+  the encoder. **Read Only.**
   
   - `<filename.d88>`
 
diff --git a/lib/imagereader/fdiimagereader.cc b/lib/imagereader/fdiimagereader.cc
index bd439902..ab17c358 100644
--- a/lib/imagereader/fdiimagereader.cc
+++ b/lib/imagereader/fdiimagereader.cc
@@ -3,6 +3,7 @@
 #include "sector.h"
 #include "imagereader/imagereader.h"
 #include "image.h"
+#include "proto.h"
 #include "lib/config.pb.h"
 #include "fmt/format.h"
 #include <algorithm>
@@ -75,6 +76,34 @@ public:
 			trackCount++;
         }
 
+        if (config.encoder().format_case() == EncoderProto::FormatCase::FORMAT_NOT_SET)
+        {
+            auto ibm = config.mutable_encoder()->mutable_ibm();
+            auto trackdata = ibm->add_trackdata();
+            trackdata->set_clock_rate_khz(500);
+            auto sectors = trackdata->mutable_sectors();
+            switch (fddType) {
+                case 0x90:
+                    std::cout << "FDI: automatically setting format to 1.2MB (1024 byte sectors)\n";
+                    config.mutable_cylinders()->set_end(76);
+                    trackdata->set_track_length_ms(167);
+                    trackdata->set_sector_size(1024);
+                    for (int i = 0; i < 9; i++)
+                        sectors->add_sector(i);
+                    break;
+                case 0x30:
+                    std::cout << "FDI: automatically setting format to 1.44MB\n";
+                    trackdata->set_track_length_ms(200);
+                    trackdata->set_sector_size(512);
+                    for (int i = 0; i < 18; i++)
+                        sectors->add_sector(i);
+                    break;
+                default:
+                    Error() << fmt::format("FDI: unknown fdd type 0x%02x, could not determine write profile automatically", fddType);
+                    break;
+            }
+        }
+
 		image->calculateSize();
 		const Geometry& geometry = image->getGeometry();
         std::cout << fmt::format("FDI: read {} tracks, {} sides, {} kB total\n",