diff --git a/ncgen/genbin.c b/ncgen/genbin.c
index e107a50ca..f24db1290 100644
--- a/ncgen/genbin.c
+++ b/ncgen/genbin.c
@@ -249,13 +249,13 @@ genbin_definespecialattributes(Symbol* var)
 		level = 9; /* default */
 	    else
 		level = special->_FilterParams[0];
-	    if(level < 0 || level > 9)
+	    if(level > 9)
 		derror("Illegal deflate level");		
 	    else {
 	        stat = nc_def_var_deflate(var->container->ncid,
 	                var->ncid,
 	                (special->_Shuffle == 1?1:0),
-	                (level >= 0?1:0),
+	                (level > 0?1:0),
 			level);
 	    }
 	} else {