diff --git a/exports/completion.elv b/exports/completion.elv
index 4e4c3bb..d3cda52 100644
--- a/exports/completion.elv
+++ b/exports/completion.elv
@@ -31,7 +31,7 @@ set edit:completion:arg-completer[pdu] = {|@words|
             cand --column-width 'Maximum widths of the tree column and width of the bar column'
             cand -m 'Minimal size proportion required to appear'
             cand --min-ratio 'Minimal size proportion required to appear'
-            cand --threads 'Set the maximum number of threads to spawn. Could be either "auto", "max", or a number'
+            cand --threads 'Set the maximum number of threads to spawn. Could be either "auto", "max", or a positive integer'
             cand --json-input 'Read JSON data from stdin'
             cand --json-output 'Print JSON data instead of an ASCII chart'
             cand -H 'Detect and subtract the sizes of hardlinks from their parent directory totals'
diff --git a/exports/completion.fish b/exports/completion.fish
index 74ceb5b..41cc644 100644
--- a/exports/completion.fish
+++ b/exports/completion.fish
@@ -8,7 +8,7 @@ complete -c pdu -s d -l max-depth -l depth -d 'Maximum depth to display the data
 complete -c pdu -s w -l total-width -l width -d 'Width of the visualization' -r
 complete -c pdu -l column-width -d 'Maximum widths of the tree column and width of the bar column' -r
 complete -c pdu -s m -l min-ratio -d 'Minimal size proportion required to appear' -r
-complete -c pdu -l threads -d 'Set the maximum number of threads to spawn. Could be either "auto", "max", or a number' -r
+complete -c pdu -l threads -d 'Set the maximum number of threads to spawn. Could be either "auto", "max", or a positive integer' -r
 complete -c pdu -l json-input -d 'Read JSON data from stdin'
 complete -c pdu -l json-output -d 'Print JSON data instead of an ASCII chart'
 complete -c pdu -s H -l deduplicate-hardlinks -l detect-links -l dedupe-links -d 'Detect and subtract the sizes of hardlinks from their parent directory totals'
diff --git a/exports/completion.ps1 b/exports/completion.ps1
index 3c1a31e..8814bf7 100644
--- a/exports/completion.ps1
+++ b/exports/completion.ps1
@@ -34,7 +34,7 @@ Register-ArgumentCompleter -Native -CommandName 'pdu' -ScriptBlock {
             [CompletionResult]::new('--column-width', '--column-width', [CompletionResultType]::ParameterName, 'Maximum widths of the tree column and width of the bar column')
             [CompletionResult]::new('-m', '-m', [CompletionResultType]::ParameterName, 'Minimal size proportion required to appear')
             [CompletionResult]::new('--min-ratio', '--min-ratio', [CompletionResultType]::ParameterName, 'Minimal size proportion required to appear')
-            [CompletionResult]::new('--threads', '--threads', [CompletionResultType]::ParameterName, 'Set the maximum number of threads to spawn. Could be either "auto", "max", or a number')
+            [CompletionResult]::new('--threads', '--threads', [CompletionResultType]::ParameterName, 'Set the maximum number of threads to spawn. Could be either "auto", "max", or a positive integer')
             [CompletionResult]::new('--json-input', '--json-input', [CompletionResultType]::ParameterName, 'Read JSON data from stdin')
             [CompletionResult]::new('--json-output', '--json-output', [CompletionResultType]::ParameterName, 'Print JSON data instead of an ASCII chart')
             [CompletionResult]::new('-H', '-H ', [CompletionResultType]::ParameterName, 'Detect and subtract the sizes of hardlinks from their parent directory totals')
diff --git a/exports/completion.zsh b/exports/completion.zsh
index 1b30b4b..dec1cef 100644
--- a/exports/completion.zsh
+++ b/exports/completion.zsh
@@ -36,7 +36,7 @@ block-count\:"Count numbers of blocks"))' \
 '*--column-width=[Maximum widths of the tree column and width of the bar column]:TREE_WIDTH:_default:TREE_WIDTH:_default' \
 '-m+[Minimal size proportion required to appear]:MIN_RATIO:_default' \
 '--min-ratio=[Minimal size proportion required to appear]:MIN_RATIO:_default' \
-'--threads=[Set the maximum number of threads to spawn. Could be either "auto", "max", or a number]:THREADS:_default' \
+'--threads=[Set the maximum number of threads to spawn. Could be either "auto", "max", or a positive integer]:THREADS:_default' \
 '(-q --quantity -H --deduplicate-hardlinks)--json-input[Read JSON data from stdin]' \
 '--json-output[Print JSON data instead of an ASCII chart]' \
 '-H[Detect and subtract the sizes of hardlinks from their parent directory totals]' \
diff --git a/src/app.rs b/src/app.rs
index c8d8905..7fad5b5 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -145,7 +145,7 @@ impl App {
                 }
             }
             Threads::Max => None,
-            Threads::Fixed(threads) => Some(threads),
+            Threads::Fixed(threads) => Some(threads.get()),
         };
 
         if let Some(threads) = threads {
diff --git a/src/args.rs b/src/args.rs
index 19951e4..db6698c 100644
--- a/src/args.rs
+++ b/src/args.rs
@@ -159,7 +159,7 @@ pub struct Args {
     #[clap(long, short)]
     pub progress: bool,
 
-    /// Set the maximum number of threads to spawn. Could be either "auto", "max", or a number.
+    /// Set the maximum number of threads to spawn. Could be either "auto", "max", or a positive integer.
     #[clap(long, default_value_t = Threads::Auto)]
     pub threads: Threads,
 
diff --git a/src/args/threads.rs b/src/args/threads.rs
index e21a754..44dc44a 100644
--- a/src/args/threads.rs
+++ b/src/args/threads.rs
@@ -1,5 +1,8 @@
 use derive_more::{Display, Error};
-use std::{num::ParseIntError, str::FromStr};
+use std::{
+    num::{NonZeroUsize, ParseIntError},
+    str::FromStr,
+};
 
 const AUTO: &str = "auto";
 const MAX: &str = "max";
@@ -12,7 +15,7 @@ pub enum Threads {
     Auto,
     #[display("{MAX}")]
     Max,
-    Fixed(usize),
+    Fixed(NonZeroUsize),
 }
 
 /// Error that occurs when parsing a string to as [`Threads`].