diff --git a/src/epanet.c b/src/epanet.c
index 71cad74..38dee56 100644
--- a/src/epanet.c
+++ b/src/epanet.c
@@ -1790,6 +1790,7 @@ int DLLEXPORT EN_setqualtype(EN_Project p, int qualType, const char *chemName,
     qual->Ctol *= Ucf[QUALITY];
     if (qual->Qualflag == CHEM) // Chemical analysis
     {
+        qual->TraceNode = 0;
         strncpy(qual->ChemName, chemName, MAXID);
         strncpy(qual->ChemUnits, chemUnits, MAXID);
         strncpy(rpt->Field[QUALITY].Units, qual->ChemUnits, MAXID);
@@ -1807,10 +1808,16 @@ int DLLEXPORT EN_setqualtype(EN_Project p, int qualType, const char *chemName,
     }
     if (qual->Qualflag == AGE) // Water age analysis
     {
+        qual->TraceNode = 0;
         strncpy(qual->ChemName, w_AGE, MAXID);
         strncpy(qual->ChemUnits, u_HOURS, MAXID);
         strcpy(rpt->Field[QUALITY].Units, u_HOURS);
     }
+    if (qual->Qualflag == NONE)
+    {
+        qual->TraceNode = 0;
+        strcpy(qual->ChemName, "");
+    }
 
     // When changing from CHEM to AGE or TRACE, nodes initial quality
     // values must be returned to their original ones
@@ -1916,6 +1923,8 @@ int DLLEXPORT EN_addnode(EN_Project p, const char *id, int nodeType, int *index)
         }
         // adjust indices of tanks/reservoirs in Rule premises (see RULES.C)
         adjusttankrules(p, 1);
+         // adjust index of trace node
+         if (qual->TraceNode > net->Njuncs - 1) qual->TraceNode += 1;
     }
 
     // Actions taken when a new Tank/Reservoir is added