diff --git a/rtengine/boxblur.cc b/rtengine/boxblur.cc
index 491ffae14..045c7ac3f 100644
--- a/rtengine/boxblur.cc
+++ b/rtengine/boxblur.cc
@@ -33,6 +33,7 @@ void boxblur(float** src, float** dst, int radius, int W, int H, bool multiThrea
 {
     //box blur using rowbuffers and linebuffers instead of a full size buffer
 
+    radius = rtengine::min(radius, W - 1, H - 1);
     if (radius == 0) {
         if (src != dst) {
 #ifdef _OPENMP
diff --git a/rtengine/cplx_wavelet_level.h b/rtengine/cplx_wavelet_level.h
index 8664606c6..09b4e4a88 100644
--- a/rtengine/cplx_wavelet_level.h
+++ b/rtengine/cplx_wavelet_level.h
@@ -272,7 +272,7 @@ template<typename T> void wavelet_level<T>::SynthesisFilterHaarVertical (const T
         #pragma omp for nowait
 #endif
 
-        for(int i = 0; i < skip; i++)
+        for(int i = 0; i < std::min(skip, height); i++)
         {
             for(int j = 0; j < width; j++) {
                 dst[width * i + j] = (srcLo[i * width + j] + srcHi[i * width + j]);
diff --git a/rtengine/ipwavelet.cc b/rtengine/ipwavelet.cc
index 91c7d6c44..7c0dc368b 100644
--- a/rtengine/ipwavelet.cc
+++ b/rtengine/ipwavelet.cc
@@ -1195,7 +1195,7 @@ void ImProcFunctions::ip_wavelet(LabImage * lab, LabImage * dst, int kall, const
                                 b = 327.68f * Chprov * sincosv.x; //aply Munsell
                             } else {//general case
                                 L = labco->L[i1][j1];
-                                const float Lin = labco->L[i1][j1];
+                                const float Lin = std::max(0.f, L);
 
                                 if(wavclCurve  && cp.finena) {
                                     labco->L[i1][j1] = (0.5f * Lin + 1.5f * wavclCurve[Lin]) / 2.f;   //apply contrast curve