diff --git a/src/ops.c b/src/ops.c
index d46a049..f4524d3 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -2919,7 +2919,7 @@
 	    for (bit = bits; bit > 0; bit--)
 		if ((n >> (bit - 1)) & 0x1) break;
 
-	    for (i = 0; bit > 0; bit--)
+	    for (i = 0; bit > 0 && i < (NUMBUFLEN - 1); bit--)
 		buf2[i++] = ((n >> (bit - 1)) & 0x1) ? '1' : '0';
 
 	    buf2[i] = '\0';