diff --git a/runtime/r_split.c b/runtime/r_split.c
index 92331fe61..ebe59d31a 100644
--- a/runtime/r_split.c
+++ b/runtime/r_split.c
@@ -39,13 +39,13 @@ int find_new_line_pivot(char *buffer, int start_pos, int end_pos, bool backward)
   if (backward) {
     for (int i = end_pos; i >= start_pos; i--) {
       if (buffer[i] == '\n')
-        return i; 
+        return i;
     }
   }
   else {
     for (int i = start_pos; i <= end_pos; i++) {
       if (buffer[i] == '\n')
-        return i; 
+        return i;
     }
   }
   return -1;
@@ -73,7 +73,7 @@ void SplitByLines(FILE *inputFile, int batchSize, FILE *outputFiles[], unsigned
     if (len < full_payload) {
       init_batch_size = len/numOutputFiles;
     }
-    
+
     for (current_file_id = 0; current_file_id < numOutputFiles; current_file_id++) {
       outputFile = outputFiles[current_file_id];
       int next_start = 0;
@@ -89,7 +89,7 @@ void SplitByLines(FILE *inputFile, int batchSize, FILE *outputFiles[], unsigned
           next_start = pivot + 1;
           blockSize = next_start - start_pos;
         }
-        
+
       } else {
         // Process output for last node
         blockSize = len - start_pos;
@@ -98,14 +98,14 @@ void SplitByLines(FILE *inputFile, int batchSize, FILE *outputFiles[], unsigned
         } else {
           is_last = false;
         }
-          
+
       }
-      
+
       if (add_header)
         writeHeader(outputFile, id, blockSize, is_last);
 
       safeWriteWithFlush(init_buffer + start_pos, 1, blockSize, outputFile);
-      
+
       start_pos = next_start;
 
       if (is_last) {
@@ -113,7 +113,7 @@ void SplitByLines(FILE *inputFile, int batchSize, FILE *outputFiles[], unsigned
       }
     }
 
-    // This will wrap around if the last chunk was complete 
+    // This will wrap around if the last chunk was complete
     // otherwise keep pointer on the last file
     if (is_last) {
       current_file_id = 0;
@@ -146,7 +146,7 @@ void SplitByLines(FILE *inputFile, int batchSize, FILE *outputFiles[], unsigned
       headSize = len;
       blockSize = prevRestSize + headSize;
       if (add_header) {
-          if (feof(inputFile)) 
+          if (feof(inputFile))
             writeHeader(outputFile, id, blockSize, 1);
           else
             writeHeader(outputFile, id, blockSize, 0);
@@ -283,8 +283,12 @@ int main(int argc, char *argv[])
   // flags: -b to use bytes (batch_size will be exact number of bytes instead of approximating to the closest line)
   if (argc < 4)
   {
-    // TODO print usage string
-    fprintf(stderr, "missing input!\n");
+    // TODO: document -r flag
+    fprintf(stderr,
+            "\n"
+            "Usage: %s [-b] [-r] input_file batch_size output_file_1 output_file_2 [output_file_3 ...]\n\n"
+            "    -b: use bytes (batch_size will be exact number of bytes instead of approximating to the closest line)\n\n",
+            argv[0]);
     exit(1);
   }
   bool useBytes = 0, offset = 0, raw = 0;