--- libgig/trunk/src/gig.cpp	2021/07/19 14:35:37	3978
+++ libgig/trunk/src/gig.cpp	2021/07/19 14:43:22	3979
@@ -6659,7 +6659,9 @@
        // this string is needed for the gig to be loadable in GSt:
        pInstrument->pInfo->Software = "Endless Wave";
 
+       const size_t idxIt = InstrumentsIterator - pInstruments->begin();
        pInstruments->push_back(pInstrument);
+       InstrumentsIterator = pInstruments->begin() + std::min(idxIt, pInstruments->size()); // avoid iterator invalidation
        return pInstrument;
     }
     
@@ -6771,7 +6773,9 @@
         if (!pInstruments) throw gig::Exception("Could not delete instrument as there are no instruments");
         InstrumentList::iterator iter = find(pInstruments->begin(), pInstruments->end(), (DLS::Instrument*) pInstrument);
         if (iter == pInstruments->end()) throw gig::Exception("Could not delete instrument, could not find given instrument");
+        const size_t idxIt = InstrumentsIterator - pInstruments->begin();
         pInstruments->erase(iter);
+        InstrumentsIterator = pInstruments->begin() + std::min(idxIt, pInstruments->size()); // avoid iterator invalidation
         pInstrument->DeleteChunks();
         delete pInstrument;
     }