diff --git a/extern/imgui_patched/imgui_internal.h b/extern/imgui_patched/imgui_internal.h
index 3ec72742e..3d6a3a1d0 100644
--- a/extern/imgui_patched/imgui_internal.h
+++ b/extern/imgui_patched/imgui_internal.h
@@ -2563,7 +2563,7 @@ struct ImGuiTableColumn
         PrevEnabledColumn = NextEnabledColumn = -1;
         SortOrder = -1;
         SortDirection = ImGuiSortDirection_None;
-        DrawChannelCurrent = DrawChannelFrozen = DrawChannelUnfrozen = (ImU8)-1;
+        DrawChannelCurrent = DrawChannelFrozen = DrawChannelUnfrozen = (ImU32)-1;
     }
 };
 
diff --git a/extern/imgui_patched/imgui_tables.cpp b/extern/imgui_patched/imgui_tables.cpp
index 9b67811c7..6aea054eb 100644
--- a/extern/imgui_patched/imgui_tables.cpp
+++ b/extern/imgui_patched/imgui_tables.cpp
@@ -1998,6 +1998,11 @@ void ImGui::TableBeginCell(ImGuiTable* table, int column_n)
     {
         // FIXME-TABLE: Could avoid this if draw channel is dummy channel?
         SetWindowClipRectBeforeSetChannel(window, column->ClipRect);
+        if (column->DrawChannelCurrent==(ImGuiTableDrawChannelIdx)-1) {
+          // temporary workaround for #502
+          //printf("sorry!\n");
+          column->DrawChannelCurrent=column_n;
+        }
         table->DrawSplitter->SetCurrentChannel(window->DrawList, column->DrawChannelCurrent);
     }
 
diff --git a/src/engine/engine.cpp b/src/engine/engine.cpp
index ea87e901e..d3d1ff23b 100644
--- a/src/engine/engine.cpp
+++ b/src/engine/engine.cpp
@@ -1852,6 +1852,9 @@ bool DivEngine::addWaveFromFile(const char* path, bool addRaw) {
         // read as .dmw
         reader.seek(0,SEEK_SET);
         int len=reader.readI();
+        if (len<=0 || len>256) {
+          throw EndOfFileException(&reader,reader.size());
+        }
         wave->max=(unsigned char)reader.readC();
         if (wave->max==255) { // new wavetable format
           unsigned char waveVersion=reader.readC();
diff --git a/src/engine/platform/zxbeeper.cpp b/src/engine/platform/zxbeeper.cpp
index 3ea42ede6..ff14d161c 100644
--- a/src/engine/platform/zxbeeper.cpp
+++ b/src/engine/platform/zxbeeper.cpp
@@ -208,6 +208,7 @@ int DivPlatformZXBeeper::dispatch(DivCommand c) {
       chan[c.chan].duty=c.value;
       break;
     case DIV_CMD_SAMPLE_MODE:
+      if (isMuted[c.chan]) break;
       curSample=c.value;
       curSamplePos=0;
       curSamplePeriod=0;