diff --git a/cjpeg.c b/cjpeg.c
index 23634aec..1d39dab8 100644
--- a/cjpeg.c
+++ b/cjpeg.c
@@ -282,8 +282,10 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
 
     } else if (keymatch(arg, "dct", 2)) {
       /* Select DCT algorithm. */
-      if (++argn >= argc)	/* advance to next argument */
+      if (++argn >= argc) { /* advance to next argument */
+        fprintf(stderr, "%s: missing argument for dct\n", progname);
 	usage();
+      }
       if (keymatch(argv[argn], "int", 1)) {
 	cinfo->dct_method = JDCT_ISLOW;
       } else if (keymatch(argv[argn], "fast", 2)) {
@@ -291,6 +293,7 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
       } else if (keymatch(argv[argn], "float", 2)) {
 	cinfo->dct_method = JDCT_FLOAT;
       } else
+        fprintf(stderr, "%s: invalid argument for dct\n", progname);
 	usage();
 
     } else if (keymatch(arg, "debug", 1) || keymatch(arg, "verbose", 1)) {
@@ -314,7 +317,7 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
     } else if (keymatch(arg, "flat", 4)) {
       cinfo->use_flat_quant_tbl = TRUE;
       jpeg_set_quality(cinfo, 75, TRUE);
-      
+
     } else if (keymatch(arg, "grayscale", 2) || keymatch(arg, "greyscale",2)) {
       /* Force a monochrome JPEG file to be generated. */
       jpeg_set_colorspace(cinfo, JCS_GRAYSCALE);
@@ -327,12 +330,12 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
       if (++argn >= argc)	/* advance to next argument */
 	usage();
       cinfo->lambda_log_scale1 = atof(argv[argn]);
-      
+
     } else if (keymatch(arg, "lambda2", 7)) {
       if (++argn >= argc)	/* advance to next argument */
 	usage();
       cinfo->lambda_log_scale2 = atof(argv[argn]);
-      
+
     } else if (keymatch(arg, "maxmemory", 3)) {
       /* Maximum memory in Kb (or Mb with 'm'). */
       long lval;
@@ -348,7 +351,7 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
 
     } else if (keymatch(arg, "multidcscan", 3)) {
       cinfo->one_dc_scan = FALSE;
-      
+
     } else if (keymatch(arg, "optimize", 1) || keymatch(arg, "optimise", 1)) {
       /* Enable entropy parm optimization. */
 #ifdef ENTROPY_OPT_SUPPORTED
@@ -361,8 +364,10 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
 
     } else if (keymatch(arg, "outfile", 4)) {
       /* Set output file name. */
-      if (++argn >= argc)	/* advance to next argument */
+      if (++argn >= argc)	{ /* advance to next argument */
+        fprintf(stderr, "%s: missing argument for outfile\n", progname);
 	usage();
+      }
       outfilename = argv[argn];	/* save it away for later use */
 
     } else if (keymatch(arg, "progressive", 1)) {
@@ -388,8 +393,10 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
 
     } else if (keymatch(arg, "quality", 1)) {
       /* Quality ratings (quantization table scaling factors). */
-      if (++argn >= argc)	/* advance to next argument */
+      if (++argn >= argc)	{ /* advance to next argument */
+        fprintf(stderr, "%s: missing argument for quality\n", progname);
 	usage();
+      }
       qualityarg = argv[argn];
 
     } else if (keymatch(arg, "qslots", 2)) {
@@ -505,6 +512,7 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
       jpeg_set_quality(cinfo, 75, TRUE);
       
     } else {
+      fprintf(stderr, "%s: unknown option '%s'\n", progname, arg);
       usage();			/* bogus switch */
     }
   }
@@ -516,20 +524,26 @@ parse_switches (j_compress_ptr cinfo, int argc, char **argv,
     /* Set quantization tables for selected quality. */
     /* Some or all may be overridden if -qtables is present. */
     if (qualityarg != NULL)	/* process -quality if it was present */
-      if (! set_quality_ratings(cinfo, qualityarg, force_baseline))
+      if (! set_quality_ratings(cinfo, qualityarg, force_baseline)) {
+        fprintf(stderr, "%s: can't set quality ratings\n", progname);
 	usage();
+      }
 
     if (qtablefile != NULL)	/* process -qtables if it was present */
-      if (! read_quant_tables(cinfo, qtablefile, force_baseline))
+      if (! read_quant_tables(cinfo, qtablefile, force_baseline)) {
+        fprintf(stderr, "%s: can't read qtable file\n", progname);
 	usage();
+      }
 
     if (qslotsarg != NULL)	/* process -qslots if it was present */
       if (! set_quant_slots(cinfo, qslotsarg))
 	usage();
 
     if (samplearg != NULL)	/* process -sample if it was present */
-      if (! set_sample_factors(cinfo, samplearg))
+      if (! set_sample_factors(cinfo, samplearg)) {
+        fprintf(stderr, "%s: can't set sample factors\n", progname);
 	usage();
+      }
 
 #ifdef C_PROGRESSIVE_SUPPORTED
     if (simple_progressive)	/* process -progressive; -scans can override */