diff --git a/tools/resampler_tools/fir.cpp b/tools/resampler_tools/fir.cpp
index cc3d509..8c8a4ea 100644
--- a/tools/resampler_tools/fir.cpp
+++ b/tools/resampler_tools/fir.cpp
@@ -243,7 +243,7 @@
             }
         }
     } else {
-        for (int j=0 ; j<polyN ; j++) {
+        for (unsigned int j=0 ; j<polyN ; j++) {
             // calculate the phase
             double p = ((polyM*j) % polyN) / double(polyN);
             if (!debug) printf("\n    ");