diff --git a/analyzer/pgmtexture.c b/analyzer/pgmtexture.c
index b694219..e33bc5c 100644
--- a/analyzer/pgmtexture.c
+++ b/analyzer/pgmtexture.c
@@ -929,7 +929,7 @@ main (int argc, const char ** argv) {
 
     FILE * ifP;
     gray ** grays;
-    unsigned int tone[PGM_MAXMAXVAL];
+    unsigned int tone[PGM_MAXMAXVAL+1];
     unsigned int r0, r45, r90;
     unsigned int d;
     unsigned int x, y;