diff --git a/lib/ftrsd/ftrsd2.c b/lib/ftrsd/ftrsd2.c
index 6da9b417b..7d8dd366a 100644
--- a/lib/ftrsd/ftrsd2.c
+++ b/lib/ftrsd/ftrsd2.c
@@ -38,7 +38,7 @@ void ftrsd2_(int mrsym[], int mrprob[], int mr2sym[], int mr2prob[],
   int nera_best=0;
   float pp,pp1,pp2;
   static unsigned int nseed;
-  
+
 // Power-percentage symbol metrics - composite gnnf/hf 
   int perr[8][8] = {
     { 4,      9,     11,     13,     14,     14,     15,     15},
@@ -203,7 +203,7 @@ NB: j is the symbol-vector index of the symbol with rank i.
   param[1]=nhard_min;
   param[2]=nsoft_min;
   param[3]=nera_best;
-  param[4]=1000.0*pp2/pp1;
+  param[4]= pp1 > 0 ? 1000.0*pp2/pp1 : 1000.0;
   param[5]=ntotal_min;
   param[6]=ntry[0];
   param[7]=1000.0*pp2;
diff --git a/map65/libm65/ftrsd2.c b/map65/libm65/ftrsd2.c
index 241312483..7d8dd366a 100644
--- a/map65/libm65/ftrsd2.c
+++ b/map65/libm65/ftrsd2.c
@@ -203,7 +203,7 @@ NB: j is the symbol-vector index of the symbol with rank i.
   param[1]=nhard_min;
   param[2]=nsoft_min;
   param[3]=nera_best;
-  param[4]=1000.0*pp2/pp1;
+  param[4]= pp1 > 0 ? 1000.0*pp2/pp1 : 1000.0;
   param[5]=ntotal_min;
   param[6]=ntry[0];
   param[7]=1000.0*pp2;