diff --git a/rtengine/LUT.h b/rtengine/LUT.h
index d83a431ca..eb22ff7f9 100644
--- a/rtengine/LUT.h
+++ b/rtengine/LUT.h
@@ -579,7 +579,7 @@ public:
             numVals = std::min(numVals, passThrough.getSize());
             float mult = dest.size - 1;
 
-            for (int i = 0; i < numVals; i++) {
+            for (unsigned int i = 0; i < numVals; i++) {
                 int hi = (int)(mult * passThrough[i]);
                 dest[hi] += this->data[i] ;
             }
diff --git a/rtengine/curves.cc b/rtengine/curves.cc
index 8f2aa03d3..3096f19f4 100644
--- a/rtengine/curves.cc
+++ b/rtengine/curves.cc
@@ -45,7 +45,7 @@ using namespace std;
 namespace rtengine
 {
 
-Curve::Curve () : N(0), ppn(0), x(nullptr), y(nullptr), mc(0.0), mfc(0.0), msc(0.0), mhc(0.0), ypp(nullptr), x1(0.0), y1(0.0), x2(0.0), y2(0.0), x3(0.0), y3(0.0), firstPointIncluded(false), increment(0.0), nbr_points(0), hashSize(1000 /* has to be initialized to the maximum value */) {}
+Curve::Curve () : N(0), ppn(0), x(nullptr), y(nullptr), mc(0.0), mfc(0.0), msc(0.0), mhc(0.0), hashSize(1000 /* has to be initialized to the maximum value */), ypp(nullptr), x1(0.0), y1(0.0), x2(0.0), y2(0.0), x3(0.0), y3(0.0), firstPointIncluded(false), increment(0.0), nbr_points(0) {}
 
 void Curve::AddPolygons ()
 {
@@ -104,7 +104,7 @@ void Curve::fillHash()
     milestone = 0.;
     polyIter = 0;
 
-    for (unsigned int i = 0; i < (hashSize + 1);) {
+    for (unsigned int i = 0; i < hashSize + 1u;) {
         while(poly_x[polyIter] < (milestone + increment)) {
             ++polyIter;
         }
@@ -1376,7 +1376,7 @@ void ColorGradientCurve::SetXYZ(const Curve *pCurve, const double xyz_rgb[3][3],
     }
 
     float r, g, b, xx, yy, zz;
-    float lr1, lr2;
+    float lr1, lr2 = 0.f;
     int upperBound = lut1.getUpperBound();
 
     if (pCurve->isIdentity()) {
@@ -1765,7 +1765,7 @@ float PerceptualToneCurve::get_curve_val(float x, float range[2], float lut[], s
 
     int idx = (int)xm;
 
-    if (idx >= lut_size - 1) {
+    if (idx >= static_cast<int>(lut_size) - 1) {
         return lut[lut_size - 1];
     }
 
@@ -1790,7 +1790,7 @@ float PerceptualToneCurve::calculateToneCurveContrastValue() const
         const float xd = 0.07;
         const float tx[] = { 0.30, 0.35, 0.40, 0.45 }; // we only look in the midtone range
 
-        for (int i = 0; i < sizeof(tx) / sizeof(tx[0]); i++) {
+        for (size_t i = 0; i < sizeof(tx) / sizeof(tx[0]); i++) {
             float x0 = tx[i] - xd;
             float y0 = CurveFactory::gamma2(lutToneCurve[CurveFactory::igamma2(x0) * 65535.f] / 65535.f) - k * x0;
             float x1 = tx[i] + xd;
@@ -1807,7 +1807,7 @@ float PerceptualToneCurve::calculateToneCurveContrastValue() const
         {
             const float tx[] = { 0.20, 0.25, 0.50, 0.55 }; // we only look in the midtone range
 
-            for (int i = 0; i < sizeof(tx) / sizeof(tx[0]); i++) {
+            for (size_t i = 0; i < sizeof(tx) / sizeof(tx[0]); i++) {
                 float x0 = tx[i] - xd;
                 float y0 = CurveFactory::gamma2(lutToneCurve[CurveFactory::igamma2(x0) * 65535.f] / 65535.f) - k * x0;
                 float x1 = tx[i] + xd;