diff --git a/.travis.yml b/.travis.yml
index d4b4368..9925ddd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -37,19 +37,19 @@ jobs:
 
     # Minimum Rust supported channel.
     - os: linux
-      rust: 1.36.0
+      rust: 1.40.0
       env: TARGET=x86_64-unknown-linux-gnu
     - os: linux
-      rust: 1.36.0
+      rust: 1.40.0
       env: TARGET=x86_64-unknown-linux-musl
     - os: linux
-      rust: 1.36.0
+      rust: 1.40.0
       env: TARGET=i686-unknown-linux-gnu
     - os: linux
-      rust: 1.36.0
+      rust: 1.40.0
       env: TARGET=i686-unknown-linux-musl
     - os: osx
-      rust: 1.36.0
+      rust: 1.40.0
       env: TARGET=x86_64-apple-darwin
 
 before_install:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index bc217be..605e280 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@
 
 ## Bugfixes
 
+- Invalid numeric command-line arguments are silently ignored, see #675
 - Disable jemalloc on Android, see #662
 
 ## Changes
diff --git a/Cargo.lock b/Cargo.lock
index 1d1707b..428d0fc 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4,137 +4,156 @@
 name = "aho-corasick"
 version = "0.7.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8716408b8bc624ed7f65d223ddb9ac2d044c0547b6fa4b0d554f3a9540496ada"
 dependencies = [
- "memchr 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "memchr",
 ]
 
 [[package]]
 name = "ansi_term"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ee49baf6cb617b853aa8d93bf420db2383fab46d314482ca2803b40d5fde979b"
 dependencies = [
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi",
 ]
 
 [[package]]
 name = "ansi_term"
 version = "0.12.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d52a9bb7ec0cf484c551830a7ce27bd20d67eac647e1befb56b0be4ee39a55d2"
 dependencies = [
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi",
 ]
 
 [[package]]
 name = "anyhow"
 version = "1.0.31"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85bb70cc08ec97ca5450e6eba421deeea5f172c0fc61f78b5357b2a8e8be195f"
 
 [[package]]
 name = "arrayref"
 version = "0.3.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4c527152e37cf757a3f78aae5a06fbeefdb07ccc535c980a3208ee3060dd544"
 
 [[package]]
 name = "arrayvec"
 version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cff77d8686867eceff3105329d4698d96c2391c176d5d03adc90c7389162b5b8"
 
 [[package]]
 name = "atty"
 version = "0.2.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
 dependencies = [
- "hermit-abi 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "hermit-abi",
+ "libc",
+ "winapi",
 ]
 
 [[package]]
 name = "autocfg"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8aac770f1885fd7e387acedd76065302551364496e46b3dd00860b2f8359b9d"
 
 [[package]]
 name = "base64"
 version = "0.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b41b7ea54a0c9d92199de89e20e58d49f02f8e699814ef3fdf266f6f748d15c7"
 
 [[package]]
 name = "bitflags"
 version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
 [[package]]
 name = "blake2b_simd"
 version = "0.5.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8fb2d74254a3a0b5cac33ac9f8ed0e44aa50378d9dbb2e5d83bd21ed1dc2c8a"
 dependencies = [
- "arrayref 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "arrayvec 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "constant_time_eq 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "arrayref",
+ "arrayvec",
+ "constant_time_eq",
 ]
 
 [[package]]
 name = "bstr"
 version = "0.2.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "31accafdb70df7871592c058eca3985b71104e15ac32f64706022c58867da931"
 dependencies = [
- "memchr 2.3.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "memchr",
 ]
 
 [[package]]
 name = "cc"
 version = "1.0.53"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "404b1fe4f65288577753b17e3b36a04596ee784493ec249bf81c7f2d2acd751c"
 
 [[package]]
 name = "cfg-if"
 version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
 [[package]]
 name = "clap"
 version = "2.33.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bdfa80d47f954d53a35a64987ca1422f495b8d6483c0fe9f7117b36c2a792129"
 dependencies = [
- "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "atty 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "term_size 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "unicode-width 0.1.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "vec_map 0.8.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ansi_term 0.11.0",
+ "atty",
+ "bitflags",
+ "strsim",
+ "term_size",
+ "textwrap",
+ "unicode-width",
+ "vec_map",
 ]
 
 [[package]]
 name = "constant_time_eq"
 version = "0.1.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "245097e9a4535ee1e3e3931fcfcd55a796a44c643e8596ff6566d68f09b87bbc"
 
 [[package]]
 name = "crossbeam-utils"
 version = "0.7.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
 dependencies = [
- "autocfg 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "autocfg",
+ "cfg-if",
+ "lazy_static",
 ]
 
 [[package]]
 name = "ctrlc"
 version = "3.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a4ba686dff9fa4c1c9636ce1010b0cf98ceb421361b0bb3d6faeec43bd217a7"
 dependencies = [
- "nix 0.17.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "nix",
+ "winapi",
 ]
 
 [[package]]
 name = "diff"
 version = "0.1.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e25ea47919b1560c4e3b7fe0aaab9becf5b84a10325ddf7db0f0ba5e1026499"
 
 [[package]]
 name = "dirs-next"
@@ -142,8 +161,8 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "1cbcf9241d9e8d106295bd496bbe2e9cffd5fa098f2a8c9e2bbcbf09773c11a8"
 dependencies = [
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "dirs-sys-next 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if",
+ "dirs-sys-next",
 ]
 
 [[package]]
@@ -152,453 +171,430 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9c60f7b8a8953926148223260454befb50c751d3c50e1c178c4fd1ace4083c9a"
 dependencies = [
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "redox_users 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc",
+ "redox_users",
+ "winapi",
 ]
 
 [[package]]
 name = "fd-find"
 version = "8.1.1"
 dependencies = [
- "ansi_term 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "anyhow 1.0.31 (registry+https://github.com/rust-lang/crates.io-index)",
- "atty 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
- "clap 2.33.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "ctrlc 3.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
- "diff 0.1.12 (registry+https://github.com/rust-lang/crates.io-index)",
- "dirs 2.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "filetime 0.2.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "globset 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
- "humantime 2.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "ignore 0.4.15 (registry+https://github.com/rust-lang/crates.io-index)",
- "jemallocator 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 1.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "lscolors 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "num_cpus 1.13.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex-syntax 0.6.17 (registry+https://github.com/rust-lang/crates.io-index)",
- "tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "users 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "version_check 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ansi_term 0.12.1",
+ "anyhow",
+ "atty",
+ "clap",
+ "ctrlc",
+ "diff",
+ "dirs-next",
+ "filetime",
+ "globset",
+ "humantime",
+ "ignore",
+ "jemallocator",
+ "lazy_static",
+ "libc",
+ "lscolors",
+ "num_cpus",
+ "regex",
+ "regex-syntax",
+ "tempdir",
+ "users",
+ "version_check",
 ]
 
 [[package]]
 name = "filetime"
 version = "0.2.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "affc17579b132fc2461adf7c575cc6e8b134ebca52c51f5411388965227dc695"
 dependencies = [
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "redox_syscall 0.1.56 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if",
+ "libc",
+ "redox_syscall",
+ "winapi",
 ]
 
 [[package]]
 name = "fnv"
 version = "1.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f9eec918d3f24069decb9af1554cad7c880e2da24a9afd88aca000531ab82c1"
 
 [[package]]
 name = "fs_extra"
 version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f2a4a2034423744d2cc7ca2068453168dcdb82c438419e639a26bd87839c674"
 
 [[package]]
 name = "fuchsia-cprng"
 version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
 
 [[package]]
 name = "getrandom"
 version = "0.1.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7abc8dd8451921606d809ba32e95b6111925cd2906060d2dcc29c070220503eb"
 dependencies = [
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "wasi 0.9.0+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if",
+ "libc",
+ "wasi",
 ]
 
 [[package]]
 name = "globset"
 version = "0.4.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7ad1da430bd7281dde2576f44c84cc3f0f7b475e7202cd503042dff01a8c8120"
 dependencies = [
- "aho-corasick 0.7.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "bstr 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "fnv 1.0.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "log 0.4.8 (registry+https://github.com/rust-lang/crates.io-index)",
- "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
+ "aho-corasick",
+ "bstr",
+ "fnv",
+ "log",
+ "regex",
 ]
 
 [[package]]
 name = "hermit-abi"
 version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "91780f809e750b0a89f5544be56617ff6b1227ee485bcb06ebe10cdf89bd3b71"
 dependencies = [
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc",
 ]
 
 [[package]]
 name = "humantime"
 version = "2.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9b6c53306532d3c8e8087b44e6580e10db51a023cf9b433cea2ac38066b92da"
 
 [[package]]
 name = "ignore"
 version = "0.4.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "128b9e89d15a3faa642ee164c998fd4fae3d89d054463cddb2c25a7baad3a352"
 dependencies = [
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- "regex 1.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
- "same-file 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
- "thread_local 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "walkdir 2.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi-util 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "crossbeam-utils",
+ "globset",
+ "lazy_static",
+ "log",
+ "memchr",
+ "regex",
+ "same-file",
+ "thread_local",
+ "walkdir",
+ "winapi-util",
 ]
 
 [[package]]
 name = "jemalloc-sys"
 version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0d3b9f3f5c9b31aa0f5ed3260385ac205db665baa41d49bb8338008ae94ede45"
 dependencies = [
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- "fs_extra 1.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc",
+ "fs_extra",
+ "libc",
 ]
 
 [[package]]
 name = "jemallocator"
 version = "0.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43ae63fcfc45e99ab3d1b29a46782ad679e98436c3169d15a167a1108a724b69"
 dependencies = [
- "jemalloc-sys 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
+ "jemalloc-sys",
+ "libc",
 ]
 
 [[package]]
 name = "lazy_static"
 version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
 version = "0.2.70"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3baa92041a6fec78c687fa0cc2b3fae8884f743d672cf551bed1d6dac6988d0f"
 
 [[package]]
 name = "log"
 version = "0.4.8"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "14b6052be84e6b71ab17edffc2eeabf5c2c3ae1fdb464aae35ac50c67a44e1f7"
 dependencies = [
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cfg-if",
 ]
 
 [[package]]
 name = "lscolors"
 version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1f77452267149eac960ded529fe5f5460ddf792845a1d71b5d0cfcee5642e47e"
 dependencies = [
- "ansi_term 0.12.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ansi_term 0.12.1",
 ]
 
 [[package]]
 name = "memchr"
 version = "2.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3728d817d99e5ac407411fa471ff9800a778d88a24685968b36824eaf4bee400"
 
 [[package]]
 name = "nix"
 version = "0.17.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50e4785f2c3b7589a0d0c1dd60285e1188adac4006e8abd6dd578e1567027363"
 dependencies = [
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- "cc 1.0.53 (registry+https://github.com/rust-lang/crates.io-index)",
- "cfg-if 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitflags",
+ "cc",
+ "cfg-if",
+ "libc",
+ "void",
 ]
 
 [[package]]
 name = "num_cpus"
 version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05499f3756671c15885fee9034446956fff3f243d6077b91e5767df161f766b3"
 dependencies = [
- "hermit-abi 0.1.13 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
+ "hermit-abi",
+ "libc",
 ]
 
 [[package]]
 name = "rand"
 version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "552840b97013b1a26992c11eac34bdd778e464601a4c2054b5f0bff7c6761293"
 dependencies = [
- "fuchsia-cprng 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "libc 0.2.70 (registry+https://github.com/rust-lang/crates.io-index)",
- "rand_core 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
- "rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
- "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+ "fuchsia-cprng",
+ "libc",
+ "rand_core 0.3.1",
+ "rdrand",
+ "winapi",
 ]
 
 [[package]]
 name = "rand_core"
 version = "0.3.1"
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-"checksum void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
-"checksum walkdir 2.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "777182bc735b6424e1a57516d35ed72cb8019d85c8c9bf536dccb3445c1a2f7d"
-"checksum wasi 0.9.0+wasi-snapshot-preview1 (registry+https://github.com/rust-lang/crates.io-index)" = "cccddf32554fecc6acb585f82a32a72e28b48f8c4c1883ddfeeeaa96f7d8e519"
-"checksum winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)" = "8093091eeb260906a183e6ae1abdba2ef5ef2257a21801128899c3fc699229c6"
-"checksum winapi-i686-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
-"checksum winapi-util 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "70ec6ce85bb158151cae5e5c87f95a8e97d2c0c4b001223f33a334e3ce5de178"
-"checksum winapi-x86_64-pc-windows-gnu 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/src/main.rs b/src/main.rs
index 24a7876..b17b5a2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -34,7 +34,12 @@ use crate::regex_helper::pattern_has_uppercase_char;
 
 // We use jemalloc for performance reasons, see https://github.com/sharkdp/fd/pull/481
 // FIXME: re-enable jemalloc on macOS, see comment in Cargo.toml file for more infos
-#[cfg(all(not(windows), not(target_os = "android"), not(target_os = "macos"), not(target_env = "musl")))]
+#[cfg(all(
+    not(windows),
+    not(target_os = "android"),
+    not(target_os = "macos"),
+    not(target_env = "musl")
+))]
 #[global_allocator]
 static ALLOC: jemallocator::Jemalloc = jemallocator::Jemalloc;
 
@@ -52,7 +57,7 @@ fn run() -> Result<ExitCode> {
         }
         env::set_current_dir(base_directory).with_context(|| {
             format!(
-                "Could not set '{}' as the current working directory.",
+                "Could not set '{}' as the current working directory",
                 base_directory.to_string_lossy()
             )
         })?;
@@ -318,22 +323,38 @@ fn run() -> Result<ExitCode> {
             .value_of("max-depth")
             .or_else(|| matches.value_of("rg-depth"))
             .or_else(|| matches.value_of("exact-depth"))
-            .and_then(|n| usize::from_str_radix(n, 10).ok()),
+            .map(|n| usize::from_str_radix(n, 10))
+            .transpose()
+            .context("Failed to parse argument to --max-depth/--exact-depth")?,
         min_depth: matches
             .value_of("min-depth")
             .or_else(|| matches.value_of("exact-depth"))
-            .and_then(|n| usize::from_str_radix(n, 10).ok()),
+            .map(|n| usize::from_str_radix(n, 10))
+            .transpose()
+            .context("Failed to parse argument to --min-depth/--exact-depth")?,
         prune: matches.is_present("prune"),
         threads: std::cmp::max(
             matches
                 .value_of("threads")
-                .and_then(|n| usize::from_str_radix(n, 10).ok())
+                .map(|n| usize::from_str_radix(n, 10))
+                .transpose()
+                .context(format!("Failed to parse number of threads"))?
+                .map(|n| {
+                    if n > 0 {
+                        Ok(n)
+                    } else {
+                        Err(anyhow!("Number of threads must be positive."))
+                    }
+                })
+                .transpose()?
                 .unwrap_or_else(num_cpus::get),
             1,
         ),
         max_buffer_time: matches
             .value_of("max-buffer-time")
-            .and_then(|n| u64::from_str_radix(n, 10).ok())
+            .map(|n| u64::from_str_radix(n, 10))
+            .transpose()
+            .context("Failed to parse max. buffer time argument")?
             .map(time::Duration::from_millis),
         ls_colors,
         interactive_terminal,
@@ -391,8 +412,10 @@ fn run() -> Result<ExitCode> {
         path_separator,
         max_results: matches
             .value_of("max-results")
-            .and_then(|n| usize::from_str_radix(n, 10).ok())
-            .filter(|&n| n != 0)
+            .map(|n| usize::from_str_radix(n, 10))
+            .transpose()
+            .context("Failed to parse --max-results argument")?
+            .filter(|&n| n > 0)
             .or_else(|| {
                 if matches.is_present("max-one-result") {
                     Some(1)
@@ -425,7 +448,7 @@ fn main() {
             process::exit(exit_code.into());
         }
         Err(err) => {
-            eprintln!("[fd error]: {}", err);
+            eprintln!("[fd error]: {:#}", err);
             process::exit(ExitCode::GeneralError.into());
         }
     }
diff --git a/tests/testenv/mod.rs b/tests/testenv/mod.rs
index 117bd64..6b58fc0 100644
--- a/tests/testenv/mod.rs
+++ b/tests/testenv/mod.rs
@@ -243,15 +243,23 @@ impl TestEnv {
     /// Assert that calling *fd* with the specified arguments produces the expected error,
     /// and does not succeed.
     pub fn assert_failure_with_error(&self, args: &[&str], expected: &str) {
-        let status = self.assert_error_subdirectory(".", args, expected);
+        let status = self.assert_error_subdirectory(".", args, Some(expected));
         if status.success() {
             panic!("error '{}' did not occur.", expected);
         }
     }
 
+    /// Assert that calling *fd* with the specified arguments does not succeed.
+    pub fn assert_failure(&self, args: &[&str]) {
+        let status = self.assert_error_subdirectory(".", args, None);
+        if status.success() {
+            panic!("Failure did not occur as expected.");
+        }
+    }
+
     /// Assert that calling *fd* with the specified arguments produces the expected error.
     pub fn assert_error(&self, args: &[&str], expected: &str) -> process::ExitStatus {
-        self.assert_error_subdirectory(".", args, expected)
+        self.assert_error_subdirectory(".", args, Some(expected))
     }
 
     /// Assert that calling *fd* in the specified path under the root working directory,
@@ -260,7 +268,7 @@ impl TestEnv {
         &self,
         path: P,
         args: &[&str],
-        expected: &str,
+        expected: Option<&str>,
     ) -> process::ExitStatus {
         // Setup *fd* command.
         let mut cmd = process::Command::new(&self.fd_exe);
@@ -270,17 +278,19 @@ impl TestEnv {
         // Run *fd*.
         let output = cmd.output().expect("fd output");
 
-        // Normalize both expected and actual output.
-        let expected_error = normalize_output(expected, true, self.normalize_line);
-        let actual_err = normalize_output(
-            &String::from_utf8_lossy(&output.stderr),
-            false,
-            self.normalize_line,
-        );
+        if let Some(expected) = expected {
+            // Normalize both expected and actual output.
+            let expected_error = normalize_output(expected, true, self.normalize_line);
+            let actual_err = normalize_output(
+                &String::from_utf8_lossy(&output.stderr),
+                false,
+                self.normalize_line,
+            );
 
-        // Compare actual output to expected output.
-        if !actual_err.trim_start().starts_with(&expected_error) {
-            panic!(format_output_error(args, &expected_error, &actual_err));
+            // Compare actual output to expected output.
+            if !actual_err.trim_start().starts_with(&expected_error) {
+                panic!(format_output_error(args, &expected_error, &actual_err));
+            }
         }
 
         return output.status;
diff --git a/tests/tests.rs b/tests/tests.rs
index b85f155..9a375f3 100644
--- a/tests/tests.rs
+++ b/tests/tests.rs
@@ -1645,3 +1645,22 @@ fn test_list_details() {
     // Make sure we can execute 'fd --list-details' without any errors.
     te.assert_success_and_get_output(".", &["--list-details"]);
 }
+
+/// Make sure that fd fails if numeric arguments can not be parsed
+#[test]
+fn test_number_parsing_errors() {
+    let te = TestEnv::new(&[], &[]);
+
+    te.assert_failure(&["--threads=a"]);
+    te.assert_failure(&["-j", ""]);
+    te.assert_failure(&["--threads=0"]);
+
+    te.assert_failure(&["--min-depth=a"]);
+    te.assert_failure(&["--max-depth=a"]);
+    te.assert_failure(&["--maxdepth=a"]);
+    te.assert_failure(&["--exact-depth=a"]);
+
+    te.assert_failure(&["--max-buffer-time=a"]);
+
+    te.assert_failure(&["--max-results=a"]);
+}