--- jpeg-recompress.c.orig	2018-08-18 07:48:36 +0000
+++ jpeg-recompress.c	2018-10-27 15:24:21 +0000
@@ -23,6 +23,7 @@
 #endif
 
 const char *COMMENT = "Compressed by jpeg-recompress";
+const int minDelta = 10;
 
 // Comparison method
 enum METHOD {
@@ -354,12 +355,14 @@
     long originalGraySize = 0;
     unsigned char *compressed = NULL;
     unsigned long compressedSize = 0;
+    unsigned long totalSize = 0;
     unsigned char *compressedGray;
     long compressedGraySize = 0;
     unsigned char *tmpImage;
     int width, height;
     unsigned char *metaBuf;
     unsigned int metaSize = 0;
+    unsigned int metaSizeCOM = strlen(COMMENT) + 4;
     FILE *file;
     char *inputPath = argv[optind];
     char *outputPath = argv[optind + 1];
@@ -486,8 +489,9 @@
             info(" at q=%i: %f\n", quality, metric);
         }
 
+        totalSize = compressedSize + metaSizeCOM + metaSize + minDelta;
         if (metric < target) {
-            if (compressedSize >= bufSize) {
+            if (totalSize >= bufSize) {
                 free(compressed);
                 free(compressedGray);
 
@@ -545,11 +549,16 @@
     free(buf);
 
     // Calculate and show savings, if any
-    int percent = (compressedSize + metaSize) * 100 / bufSize;
-    unsigned long saved = (bufSize > compressedSize) ? bufSize - compressedSize - metaSize : 0;
+    int percent = totalSize * 100 / bufSize;
+    unsigned long saved = (bufSize > totalSize) ? bufSize - totalSize : 0;
     info("New size is %i%% of original (saved %lu kb)\n", percent, saved / 1024);
 
-    if (compressedSize >= bufSize) {
+    // debug sizes
+    //info("compressedSize is %i, ", compressedSize);
+    //info("metaSize is %i, ", metaSize);
+    //info("totalSize is %i\n", totalSize);
+
+    if ( (totalSize) >= bufSize ) {
         error("output file is larger than input, aborting!");
         return 1;
     }