diff --git a/implot.cpp b/implot.cpp
index 24e613b..f9b3fe4 100644
--- a/implot.cpp
+++ b/implot.cpp
@@ -1171,12 +1171,10 @@ void EndPlot() {
 
     // AXIS STATES ------------------------------------------------------------
 
-    const bool flip_x     = HasFlag(plot.XAxis.Flags, ImAxisFlags_Invert);
     const bool lock_x_min = HasFlag(plot.XAxis.Flags, ImAxisFlags_LockMin);
     const bool lock_x_max = HasFlag(plot.XAxis.Flags, ImAxisFlags_LockMax);
     const bool lock_x     = (lock_x_min && lock_x_max) || (gp.NextPlotData.HasXRange && gp.NextPlotData.XRangeCond == ImGuiCond_Always);
 
-    const bool flip_y     = HasFlag(plot.YAxis.Flags, ImAxisFlags_Invert);
     const bool lock_y_min = HasFlag(plot.YAxis.Flags, ImAxisFlags_LockMin);
     const bool lock_y_max = HasFlag(plot.YAxis.Flags, ImAxisFlags_LockMax);
     const bool lock_y     = (lock_y_min && lock_y_max) || (gp.NextPlotData.HasYRange && gp.NextPlotData.YRangeCond == ImGuiCond_Always);
@@ -2151,7 +2149,7 @@ inline void DrawPieSlice(ImDrawList& DrawList, const ImVec2& center, float radiu
 }
 
 
-void PlotPieChart(char** label_ids, float* values, int count, const ImVec2& center, float radius, bool show_percents, float angle0) {
+void PlotPieChart(const char** label_ids, float* values, int count, const ImVec2& center, float radius, bool show_percents, float angle0) {
     IM_ASSERT_USER_ERROR(gp.CurrentPlot != NULL, "PlotPieChart() Needs to be called between BeginPlot() and EndPlot()!");
     ImDrawList & DrawList = *GetWindowDrawList();
 
diff --git a/implot.h b/implot.h
index 83af945..b5ceeb5 100644
--- a/implot.h
+++ b/implot.h
@@ -170,7 +170,7 @@ void PlotErrorBars(const char* label_id, const float* xs, const float* ys, const
 void PlotErrorBars(const char* label_id, const float* xs, const float* ys, const float* neg, const float* pos, int count, int offset = 0, int stride = sizeof(float));
 void PlotErrorBars(const char* label_id, ImVec4 (*getter)(void* data, int idx), void* data, int count, int offset = 0);
 // Plots a pie chart. If the sum of values > 1, each value will be normalized. Center and radius are in plot coordinates.
-void PlotPieChart(char** label_ids, float* values, int count, const ImVec2& center, float radius, bool show_percents = true, float angle0 = 90);
+void PlotPieChart(const char** label_ids, float* values, int count, const ImVec2& center, float radius, bool show_percents = true, float angle0 = 90);
 // Plots a text label at point x,y.
 void PlotLabel(const char* text, float x, float y, bool vertical = false, const ImVec2& pixel_offset = ImVec2(0,0));
 
diff --git a/implot_demo.cpp b/implot_demo.cpp
index c200541..6ea85b3 100644
--- a/implot_demo.cpp
+++ b/implot_demo.cpp
@@ -212,7 +212,7 @@ void ShowImPlotDemoWindow(bool* p_open) {
     }
     //-------------------------------------------------------------------------
     if (ImGui::CollapsingHeader("Pie Charts")) {
-        static char* labels1[]   = {"Frogs","Hogs","Dogs","Logs"};
+        static const char* labels1[]   = {"Frogs","Hogs","Dogs","Logs"};
         static float pre_normalized[] = {0.15f,  0.30f,  0.45f, 0.10f};
         ImVec2 center(0.5f,0.5f); // in plot units, not pixels
         float radius = 0.4f;      // in plot units, not pixels
@@ -233,7 +233,7 @@ void ShowImPlotDemoWindow(bool* p_open) {
         };
         ImGui::SetPlotPalette(YlOrRd, 5);
         SetNextPlotRange(0,1,0,1,ImGuiCond_Always);
-        static char* labels2[]   = {"One","Two","Three","Four","Five"};
+        static const char* labels2[]   = {"One","Two","Three","Four","Five"};
         static float not_normalized[] = {1,2,3,4,5};
         if (ImGui::BeginPlot("##Pie2", NULL, NULL, ImVec2(250,250), ImPlotFlags_Legend, 0, 0)) {
             ImGui::PlotPieChart(labels2, not_normalized, 5, center, radius);