diff --git a/tools/codes_split_file.c b/tools/codes_split_file.c
index 9b0a8a05f..00166bf56 100644
--- a/tools/codes_split_file.c
+++ b/tools/codes_split_file.c
@@ -48,11 +48,11 @@ static int split_file(FILE* in, const char* filename, const int nchunks, unsigne
     fseeko(in, 0, SEEK_END);
     insize = ftello(in);
     fseeko(in, 0, SEEK_SET);
-    if(nchunks == -1){
-      chunk_size = size;
-    }else{
-      assert(nchunks > 0);
-      chunk_size=insize/nchunks;
+    if (nchunks == -1) {
+        chunk_size = size;
+    } else {
+        assert(nchunks > 0);
+        chunk_size=insize/nchunks;
     }
 
     i=1;
diff --git a/tools/codes_split_file.desc b/tools/codes_split_file.desc
index d7245929e..8903f5bfa 100644
--- a/tools/codes_split_file.desc
+++ b/tools/codes_split_file.desc
@@ -3,6 +3,7 @@ NAME	codes_split_file
 DESCRIPTION
 
 	Split an input file (GRIB, BUFR etc) into chunks of roughly the same size. The output files are named input_01, input_02 etc. This is much faster than grib_copy/bufr_copy.
+	If the nchunks argument is -1, then the file is split into the individual messages.
 
 USAGE
 	codes_split_file [-v] nchunks input