diff --git a/rtengine/improccoordinator.cc b/rtengine/improccoordinator.cc
index 3609617be..7ae814f8c 100644
--- a/rtengine/improccoordinator.cc
+++ b/rtengine/improccoordinator.cc
@@ -133,7 +133,9 @@ ImProcCoordinator::ImProcCoordinator() :
 
     histLRETI(256),
 
+    vectorscopeScale(0),
     vectorscope(VECTORSCOPE_SIZE, VECTORSCOPE_SIZE),
+    waveformScale(0),
     waveformRed(0, 0),
     waveformGreen(0, 0),
     waveformBlue(0, 0),
@@ -1861,8 +1863,9 @@ void ImProcCoordinator::updateVectorscope()
     memset((int*)vectorscope, 0, size * size * sizeof(vectorscope[0][0]));
 
     const int lab_img_size = (hListener->vectorscopeType() == 1) ? (x2 - x1) * (y2 - y1) : 0;
-    float L[lab_img_size], a[lab_img_size], b[lab_img_size];
+    float a[lab_img_size], b[lab_img_size];
     if (lab_img_size) {
+        float L[lab_img_size];
         ipf.rgb2lab(*workimg, x1, y1, x2 - x1, y2 - y1, L, a, b, params->icm);
     }
 
@@ -1874,11 +1877,11 @@ void ImProcCoordinator::updateVectorscope()
             switch (hListener->vectorscopeType()) {
                 case 0: {
                     // HS
-                    int r = 256 * workimg->data[ofs++];
-                    int g = 256 * workimg->data[ofs++];
-                    int b = 256 * workimg->data[ofs++];
+                    int red = 256 * workimg->data[ofs++];
+                    int green = 256 * workimg->data[ofs++];
+                    int blue = 256 * workimg->data[ofs++];
                     float h, s, l;
-                    Color::rgb2hsl(r, g, b, h, s, l);
+                    Color::rgb2hsl(red, green, blue, h, s, l);
                     const int col = s * cos(2 * RT_PI * h) * (size / 2) + size / 2;
                     const int row = s * sin(2 * RT_PI * h) * (size / 2) + size / 2;
                     if (col >= 0 && col < size && row >= 0 && row < size) {
diff --git a/rtgui/histogrampanel.cc b/rtgui/histogrampanel.cc
index 416a114fd..65e2acfdf 100644
--- a/rtgui/histogrampanel.cc
+++ b/rtgui/histogrampanel.cc
@@ -886,8 +886,10 @@ void HistogramRGBAreaVert::get_preferred_width_for_height_vfunc (int height, int
 //
 // HistogramArea
 HistogramArea::HistogramArea (DrawModeListener *fml) :
+    vectorscope_scale(0),
     vect(0, 0),
     vect_buffer_dirty(true), vect_buffer_size(0),
+    waveform_scale(0),
     rwave(0, 0), gwave(0, 0),bwave(0, 0), lwave(0, 0),
     wave_buffer_dirty(true),
     valid(false), drawMode(options.histogramDrawMode), myDrawModeListener(fml),
@@ -1492,7 +1494,7 @@ void HistogramArea::drawWaveform(Cairo::RefPtr<Cairo::Context> &cr, int w, int h
                 const unsigned char g = needGreen ? min<float>(scale * g_row[col], 0xff) : 0;
                 const unsigned char b = needBlue ? min<float>(scale * b_row[col], 0xff) : 0;
                 const unsigned char value = (r > g && r > b) ? r : ((g > b) ? g : b);
-                if (value <= 0) {
+                if (value == 0) {
                     buffer_row[col] = 0;
                 } else {
                     // Speedup with one memory access instead of four.