diff --git a/examples/cwebp.c b/examples/cwebp.c
index fa337b8e..e0284470 100644
--- a/examples/cwebp.c
+++ b/examples/cwebp.c
@@ -710,6 +710,7 @@ int main(int argc, const char *argv[]) {
   }
 
   for (c = 1; c < argc; ++c) {
+    int parse_error = 0;
     if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
       HelpShort();
       return 0;
@@ -733,26 +734,27 @@ int main(int argc, const char *argv[]) {
     } else if (!strcmp(argv[c], "-short")) {
       ++short_output;
     } else if (!strcmp(argv[c], "-s") && c < argc - 2) {
-      picture.width = strtol(argv[++c], NULL, 0);
-      picture.height = strtol(argv[++c], NULL, 0);
+      picture.width = ExUtilGetInt(argv[++c], 0, &parse_error);
+      picture.height = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-m") && c < argc - 1) {
-      config.method = strtol(argv[++c], NULL, 0);
+      config.method = ExUtilGetInt(argv[++c], 0, &parse_error);
       use_lossless_preset = 0;   // disable -z option
     } else if (!strcmp(argv[c], "-q") && c < argc - 1) {
-      config.quality = (float)strtod(argv[++c], NULL);
+      config.quality = ExUtilGetFloat(argv[++c], &parse_error);
       use_lossless_preset = 0;   // disable -z option
     } else if (!strcmp(argv[c], "-z") && c < argc - 1) {
-      lossless_preset = strtol(argv[++c], NULL, 0);
+      lossless_preset = ExUtilGetInt(argv[++c], 0, &parse_error);
       if (use_lossless_preset != 0) use_lossless_preset = 1;
     } else if (!strcmp(argv[c], "-alpha_q") && c < argc - 1) {
-      config.alpha_quality = strtol(argv[++c], NULL, 0);
+      config.alpha_quality = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-alpha_method") && c < argc - 1) {
-      config.alpha_compression = strtol(argv[++c], NULL, 0);
+      config.alpha_compression = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-alpha_cleanup")) {
       keep_alpha = keep_alpha ? 2 : 0;
     } else if (!strcmp(argv[c], "-blend_alpha") && c < argc - 1) {
       blend_alpha = 1;
-      background_color = strtol(argv[++c], NULL, 16);  // <- parses '0x' prefix
+      // background color is given in hex with an optional '0x' prefix
+      background_color = ExUtilGetInt(argv[++c], 16, &parse_error);
       background_color = background_color & 0x00ffffffu;
     } else if (!strcmp(argv[c], "-alpha_filter") && c < argc - 1) {
       ++c;
@@ -771,7 +773,7 @@ int main(int argc, const char *argv[]) {
     } else if (!strcmp(argv[c], "-lossless")) {
       config.lossless = 1;
     } else if (!strcmp(argv[c], "-near_lossless") && c < argc - 1) {
-      config.near_lossless = strtol(argv[++c], NULL, 0);
+      config.near_lossless = ExUtilGetInt(argv[++c], 0, &parse_error);
       config.lossless = 1;  // use near-lossless only with lossless
     } else if (!strcmp(argv[c], "-hint") && c < argc - 1) {
       ++c;
@@ -786,13 +788,13 @@ int main(int argc, const char *argv[]) {
         goto Error;
       }
     } else if (!strcmp(argv[c], "-size") && c < argc - 1) {
-      config.target_size = strtol(argv[++c], NULL, 0);
+      config.target_size = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-psnr") && c < argc - 1) {
-      config.target_PSNR = (float)strtod(argv[++c], NULL);
+      config.target_PSNR = ExUtilGetFloat(argv[++c], &parse_error);
     } else if (!strcmp(argv[c], "-sns") && c < argc - 1) {
-      config.sns_strength = strtol(argv[++c], NULL, 0);
+      config.sns_strength = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-f") && c < argc - 1) {
-      config.filter_strength = strtol(argv[++c], NULL, 0);
+      config.filter_strength = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-af")) {
       config.autofilter = 1;
     } else if (!strcmp(argv[c], "-jpeg_like")) {
@@ -806,26 +808,26 @@ int main(int argc, const char *argv[]) {
     } else if (!strcmp(argv[c], "-nostrong")) {
       config.filter_type = 0;
     } else if (!strcmp(argv[c], "-sharpness") && c < argc - 1) {
-      config.filter_sharpness = strtol(argv[++c], NULL, 0);
+      config.filter_sharpness = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-pass") && c < argc - 1) {
-      config.pass = strtol(argv[++c], NULL, 0);
+      config.pass = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-pre") && c < argc - 1) {
-      config.preprocessing = strtol(argv[++c], NULL, 0);
+      config.preprocessing = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-segments") && c < argc - 1) {
-      config.segments = strtol(argv[++c], NULL, 0);
+      config.segments = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-partition_limit") && c < argc - 1) {
-      config.partition_limit = strtol(argv[++c], NULL, 0);
+      config.partition_limit = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-map") && c < argc - 1) {
-      picture.extra_info_type = strtol(argv[++c], NULL, 0);
+      picture.extra_info_type = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-crop") && c < argc - 4) {
       crop = 1;
-      crop_x = strtol(argv[++c], NULL, 0);
-      crop_y = strtol(argv[++c], NULL, 0);
-      crop_w = strtol(argv[++c], NULL, 0);
-      crop_h = strtol(argv[++c], NULL, 0);
+      crop_x = ExUtilGetInt(argv[++c], 0, &parse_error);
+      crop_y = ExUtilGetInt(argv[++c], 0, &parse_error);
+      crop_w = ExUtilGetInt(argv[++c], 0, &parse_error);
+      crop_h = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-resize") && c < argc - 2) {
-      resize_w = strtol(argv[++c], NULL, 0);
-      resize_h = strtol(argv[++c], NULL, 0);
+      resize_w = ExUtilGetInt(argv[++c], 0, &parse_error);
+      resize_h = ExUtilGetInt(argv[++c], 0, &parse_error);
 #ifndef WEBP_DLL
     } else if (!strcmp(argv[c], "-noasm")) {
       VP8GetCPUInfo = NULL;
@@ -920,6 +922,11 @@ int main(int argc, const char *argv[]) {
     } else {
       in_file = argv[c];
     }
+
+    if (parse_error) {
+      HelpLong();
+      return -1;
+    }
   }
   if (in_file == NULL) {
     fprintf(stderr, "No input file specified!\n");
diff --git a/examples/dwebp.c b/examples/dwebp.c
index fe80dfe3..8c884577 100644
--- a/examples/dwebp.c
+++ b/examples/dwebp.c
@@ -582,6 +582,7 @@ int main(int argc, const char *argv[]) {
   }
 
   for (c = 1; c < argc; ++c) {
+    int parse_error = 0;
     if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
       Help();
       return 0;
@@ -617,17 +618,18 @@ int main(int argc, const char *argv[]) {
     } else if (!strcmp(argv[c], "-nodither")) {
       config.options.dithering_strength = 0;
     } else if (!strcmp(argv[c], "-dither") && c < argc - 1) {
-      config.options.dithering_strength = strtol(argv[++c], NULL, 0);
+      config.options.dithering_strength =
+          ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-crop") && c < argc - 4) {
       config.options.use_cropping = 1;
-      config.options.crop_left   = strtol(argv[++c], NULL, 0);
-      config.options.crop_top    = strtol(argv[++c], NULL, 0);
-      config.options.crop_width  = strtol(argv[++c], NULL, 0);
-      config.options.crop_height = strtol(argv[++c], NULL, 0);
+      config.options.crop_left   = ExUtilGetInt(argv[++c], 0, &parse_error);
+      config.options.crop_top    = ExUtilGetInt(argv[++c], 0, &parse_error);
+      config.options.crop_width  = ExUtilGetInt(argv[++c], 0, &parse_error);
+      config.options.crop_height = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-scale") && c < argc - 2) {
       config.options.use_scaling = 1;
-      config.options.scaled_width  = strtol(argv[++c], NULL, 0);
-      config.options.scaled_height = strtol(argv[++c], NULL, 0);
+      config.options.scaled_width  = ExUtilGetInt(argv[++c], 0, &parse_error);
+      config.options.scaled_height = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-flip")) {
       config.options.flip = 1;
     } else if (!strcmp(argv[c], "-v")) {
@@ -648,6 +650,11 @@ int main(int argc, const char *argv[]) {
     } else {
       in_file = argv[c];
     }
+
+    if (parse_error) {
+      Help();
+      return -1;
+    }
   }
 
   if (in_file == NULL) {
diff --git a/examples/example_util.c b/examples/example_util.c
index 5e34f305..f64cfd80 100644
--- a/examples/example_util.c
+++ b/examples/example_util.c
@@ -23,6 +23,35 @@
 #include "webp/decode.h"
 #include "./stopwatch.h"
 
+//------------------------------------------------------------------------------
+// String parsing
+
+uint32_t ExUtilGetUInt(const char* const v, int base, int* const error) {
+  char* end = NULL;
+  const uint32_t n = (v != NULL) ? (uint32_t)strtoul(v, &end, base) : 0u;
+  if (end == v && error != NULL && !*error) {
+    *error = 1;
+    fprintf(stderr, "Error! '%s' is not an integer.\n",
+            (v != NULL) ? v : "(null)");
+  }
+  return n;
+}
+
+int ExUtilGetInt(const char* const v, int base, int* const error) {
+  return (int)ExUtilGetUInt(v, base, error);
+}
+
+float ExUtilGetFloat(const char* const v, int* const error) {
+  char* end = NULL;
+  const float f = (v != NULL) ? (float)strtod(v, &end) : 0.f;
+  if (end == v && error != NULL && !*error) {
+    *error = 1;
+    fprintf(stderr, "Error! '%s' is not a floating point number.\n",
+            (v != NULL) ? v : "(null)");
+  }
+  return f;
+}
+
 // -----------------------------------------------------------------------------
 // File I/O
 
diff --git a/examples/example_util.h b/examples/example_util.h
index 4ef703da..8e8e8014 100644
--- a/examples/example_util.h
+++ b/examples/example_util.h
@@ -20,6 +20,19 @@
 extern "C" {
 #endif
 
+//------------------------------------------------------------------------------
+// String parsing
+
+// Parses 'v' using strto(ul|l|d)(). If error is non-NULL, '*error' is set to
+// true on failure while on success it is left unmodified to allow chaining of
+// calls. An error is only printed on the first occurrence.
+uint32_t ExUtilGetUInt(const char* const v, int base, int* const error);
+int ExUtilGetInt(const char* const v, int base, int* const error);
+float ExUtilGetFloat(const char* const v, int* const error);
+
+//------------------------------------------------------------------------------
+// File I/O
+
 // Reopen file in binary (O_BINARY) mode.
 // Returns 'file' on success, NULL otherwise.
 FILE* ExUtilSetBinaryMode(FILE* file);
diff --git a/examples/gif2webp.c b/examples/gif2webp.c
index 6cfe95ba..385f19cd 100644
--- a/examples/gif2webp.c
+++ b/examples/gif2webp.c
@@ -296,6 +296,7 @@ int main(int argc, const char *argv[]) {
   }
 
   for (c = 1; c < argc; ++c) {
+    int parse_error = 0;
     if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
       Help();
       return 0;
@@ -307,17 +308,17 @@ int main(int argc, const char *argv[]) {
       allow_mixed = 1;
       config.lossless = 0;
     } else if (!strcmp(argv[c], "-q") && c < argc - 1) {
-      config.quality = (float)strtod(argv[++c], NULL);
+      config.quality = ExUtilGetFloat(argv[++c], &parse_error);
     } else if (!strcmp(argv[c], "-m") && c < argc - 1) {
-      config.method = strtol(argv[++c], NULL, 0);
+      config.method = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-kmax") && c < argc - 1) {
-      kmax = strtoul(argv[++c], NULL, 0);
+      kmax = ExUtilGetUInt(argv[++c], 0, &parse_error);
       default_kmax = 0;
     } else if (!strcmp(argv[c], "-kmin") && c < argc - 1) {
-      kmin = strtoul(argv[++c], NULL, 0);
+      kmin = ExUtilGetUInt(argv[++c], 0, &parse_error);
       default_kmin = 0;
     } else if (!strcmp(argv[c], "-f") && c < argc - 1) {
-      config.filter_strength = strtol(argv[++c], NULL, 0);
+      config.filter_strength = ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-metadata") && c < argc - 1) {
       static const struct {
         const char* option;
@@ -381,6 +382,11 @@ int main(int argc, const char *argv[]) {
     } else {
       in_file = argv[c];
     }
+
+    if (parse_error) {
+      Help();
+      return -1;
+    }
   }
 
   // Appropriate default kmin, kmax values for lossy and lossless.
diff --git a/examples/vwebp.c b/examples/vwebp.c
index 589f0832..cc64dd56 100644
--- a/examples/vwebp.c
+++ b/examples/vwebp.c
@@ -404,6 +404,7 @@ int main(int argc, char *argv[]) {
   kParams.use_color_profile = 1;
 
   for (c = 1; c < argc; ++c) {
+    int parse_error = 0;
     if (!strcmp(argv[c], "-h") || !strcmp(argv[c], "-help")) {
       Help();
       return 0;
@@ -416,7 +417,8 @@ int main(int argc, char *argv[]) {
     } else if (!strcmp(argv[c], "-noalphadither")) {
       config->options.alpha_dithering_strength = 0;
     } else if (!strcmp(argv[c], "-dither") && c + 1 < argc) {
-      config->options.dithering_strength = strtol(argv[++c], NULL, 0);
+      config->options.dithering_strength =
+          ExUtilGetInt(argv[++c], 0, &parse_error);
     } else if (!strcmp(argv[c], "-info")) {
       kParams.print_info = 1;
     } else if (!strcmp(argv[c], "-version")) {
@@ -439,6 +441,11 @@ int main(int argc, char *argv[]) {
     } else {
       kParams.file_name = argv[c];
     }
+
+    if (parse_error) {
+      Help();
+      return -1;
+    }
   }
 
   if (kParams.file_name == NULL) {
diff --git a/examples/webpmux.c b/examples/webpmux.c
index 8899ed8d..f3874920 100644
--- a/examples/webpmux.c
+++ b/examples/webpmux.c
@@ -839,14 +839,16 @@ static int GetFrameFragment(const WebPMux* mux,
   WebPMux* mux_single = NULL;
   long num = 0;
   int ok = 1;
+  int parse_error = 0;
   const WebPChunkId id = is_frame ? WEBP_CHUNK_ANMF : WEBP_CHUNK_FRGM;
   WebPMuxFrameInfo info;
   WebPDataInit(&info.bitstream);
 
-  num = strtol(config->feature_.args_[0].params_, NULL, 10);
+  num = ExUtilGetInt(config->feature_.args_[0].params_, 10, &parse_error);
   if (num < 0) {
     ERROR_GOTO1("ERROR: Frame/Fragment index must be non-negative.\n", ErrGet);
   }
+  if (parse_error) goto ErrGet;
 
   err = WebPMuxGetFrame(mux, num, &info);
   if (err == WEBP_MUX_OK && info.id != id) err = WEBP_MUX_NOT_FOUND;
@@ -934,8 +936,9 @@ static int Process(const WebPMuxConfig* config) {
                 break;
               }
               case SUBTYPE_LOOP: {
-                const long loop_count =
-                    strtol(feature->args_[i].params_, NULL, 10);
+                int parse_error = 0;
+                const int loop_count =
+                    ExUtilGetInt(feature->args_[i].params_, 10, &parse_error);
                 if (loop_count != (int)loop_count) {
                   // Note: This is only a 'necessary' condition for loop_count
                   // to be valid. The 'sufficient' conditioned in checked in
@@ -943,6 +946,7 @@ static int Process(const WebPMuxConfig* config) {
                   ERROR_GOTO1("ERROR: Loop count must be in the range 0 to "
                               "65535.\n", Err2);
                 }
+                if (parse_error) goto Err2;
                 params.loop_count = (int)loop_count;
                 break;
               }