diff --git a/rtengine/ipresize.cc b/rtengine/ipresize.cc
index b3275b2e4..f33b8f0c9 100644
--- a/rtengine/ipresize.cc
+++ b/rtengine/ipresize.cc
@@ -231,7 +231,7 @@ void ImProcFunctions::Lanczos (const LabImage* src, LabImage* dst, float scale)
         float* const la = aligned_buffer_la.data;
         float* const lb = aligned_buffer_lb.data;
         // weights for interpolation in y direction
-        float w[support] ALIGNED64;
+        float w[support] ALIGNED64 = {};
 
         // Phase 2: do actual interpolation
 #ifdef _OPENMP