diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index 80fbb5ca..a8fd95a4 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -1428,6 +1428,10 @@ bool DivEngine::addWaveFromFile(const char* path) {
     fclose(f);
     return false;
   }
+  if (len==(SIZE_MAX>>1)) {
+    fclose(f);
+    return false;
+  }
   if (len==0) {
     fclose(f);
     return false;
@@ -1620,6 +1624,14 @@ int DivEngine::addSampleFromFile(const char* path) {
         return -1;
       }
 
+      if (len==(SIZE_MAX>>1)) {
+        fclose(f);
+        BUSY_END;
+        lastError="file is invalid!";
+        delete sample;
+        return -1;
+      }
+
       if (fseek(f,0,SEEK_SET)<0) {
         fclose(f);
         BUSY_END;
diff --git a/src/engine/fileOpsIns.cpp b/src/engine/fileOpsIns.cpp
index 1173d59a..521ab424 100644
--- a/src/engine/fileOpsIns.cpp
+++ b/src/engine/fileOpsIns.cpp
@@ -1220,6 +1220,11 @@ std::vector<DivInstrument*> DivEngine::instrumentFromFile(const char* path) {
     fclose(f);
     return ret;
   }
+  if (len==(SIZE_MAX>>1)) {
+    lastError=strerror(errno);
+    fclose(f);
+    return ret;
+  }
   if (len==0) {
     lastError=strerror(errno);
     fclose(f);
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 4aa37b81..ddd52592 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -1286,6 +1286,7 @@ void FurnaceGUI::openFileDialog(FurnaceGUIFileDialogs type) {
       );
       break;
     case GUI_FILE_INS_OPEN:
+      prevIns=-3;
       if (!dirExists(workingDirIns)) workingDirIns=getHomeDir();
       hasOpened=fileDialog->openLoad(
         "Load Instrument",
@@ -1298,6 +1299,9 @@ void FurnaceGUI::openFileDialog(FurnaceGUIFileDialogs type) {
           std::vector<DivInstrument*> instruments=e->instrumentFromFile(path);
           if (!instruments.empty()) {
             e->loadTempIns(instruments[0]);
+            if (curIns!=-2) {
+              prevIns=curIns;
+            }
             curIns=-2;
           }
           for (DivInstrument* i: instruments) delete i;
@@ -2937,6 +2941,9 @@ bool FurnaceGUI::loop() {
           workingDirLayout=fileDialog->getPath()+DIR_SEPARATOR_STR;
           break;
       }
+      if (prevIns!=-3) {
+        curIns=prevIns;
+      }
       if (fileDialog->accepted()) {
         fileName=fileDialog->getFileName();
         if (fileName!="") {
@@ -3791,6 +3798,7 @@ FurnaceGUI::FurnaceGUI():
   curSample(0),
   curOctave(3),
   curOrder(0),
+  prevIns(0),
   oldRow(0),
   oldOrder(0),
   oldOrder1(0),
diff --git a/src/gui/gui.h b/src/gui/gui.h
index 98a86112..91c17b3f 100644
--- a/src/gui/gui.h
+++ b/src/gui/gui.h
@@ -931,7 +931,7 @@ class FurnaceGUI {
 
   char finalLayoutPath[4096];
 
-  int curIns, curWave, curSample, curOctave, curOrder, oldRow, oldOrder, oldOrder1, editStep, exportLoops, soloChan, soloTimeout, orderEditMode, orderCursor;
+  int curIns, curWave, curSample, curOctave, curOrder, prevIns, oldRow, oldOrder, oldOrder1, editStep, exportLoops, soloChan, soloTimeout, orderEditMode, orderCursor;
   int loopOrder, loopRow, loopEnd, isClipping, extraChannelButtons, patNameTarget, newSongCategory, latchTarget;
   int wheelX, wheelY;