diff --git a/src/dryrun.c b/src/dryrun.c
index 94f7d845..dde53cc2 100644
--- a/src/dryrun.c
+++ b/src/dryrun.c
@@ -557,12 +557,10 @@ static void dryrun_enable(PROGRAMMER *pgm, const AVRPART *p) {
     } else if(mem_is_sigrow(m) && m->size >= 6) {
       prodsigm = m;
       memset(m->buf, 0xff, m->size);
-      if(q->prog_modes & PM_PDI) {
-        m->buf[0] = m->buf[1] = 'U';
-      } else if(q->prog_modes & PM_Classic) { // Signature at even addresses
+      // Classic parts: signature at even addresses @@@ but not t102/t104
+      if(q->prog_modes & PM_Classic)
         for(int i=0; i<3; i++)
           m->buf[2*i] = q->signature[i];
-      }
     } else if(mem_is_io(m)) { // Initialise reset values (if known)
       int nr;
       const Register_file *rf = avr_locate_register_file(q, &nr);
@@ -575,7 +573,7 @@ static void dryrun_enable(PROGRAMMER *pgm, const AVRPART *p) {
     }
   }
   if(prodsigm) {
-    if(q->prog_modes & PM_UPDI) {
+    if(q->prog_modes & (PM_UPDI | PM_PDI)) {
       for (LNODEID ln=lfirst(q->mem); ln; ln=lnext(ln)) {
         AVRMEM *m = ldata(ln);
         if(m->buf == prodsigm->buf) // Skip prodsig memory
@@ -588,7 +586,7 @@ static void dryrun_enable(PROGRAMMER *pgm, const AVRPART *p) {
       }
     }
     if((q->prog_modes & PM_Classic) && (calm = avr_locate_calibration(q))) {
-      // Calibration bytes of classic parts are interspersed with signature
+      // Calibration bytes of classic parts are interspersed with signature @@@ but not t102/104
       for(int i=0; i<calm->size; i++)
         if(2*i+1 < prodsigm->size)
           prodsigm->buf[2*i+1] = 'U';