diff --git a/Library/Homebrew/completions/fish.erb b/Library/Homebrew/completions/fish.erb
index 02769bee55d6d..2d75db2d5965d 100644
--- a/Library/Homebrew/completions/fish.erb
+++ b/Library/Homebrew/completions/fish.erb
@@ -130,11 +130,11 @@ function __fish_brew_suggest_casks_all -d "Lists locally available casks"
 end
 
 function __fish_brew_suggest_casks_installed -d "Lists installed casks"
-    command ls -1 (brew --caskroom)
+    command ls -1 (brew --caskroom) 2>/dev/null
 end
 
 function __fish_brew_suggest_casks_outdated -d "Lists outdated casks with the information about potential upgrade"
-    brew outdated --cask --verbose \
+    brew outdated --cask --verbose 2>/dev/null \
         # replace first space with tab to make the following a description in the completions list:
         | string replace -r '\s' '\t'
 end
diff --git a/completions/fish/brew.fish b/completions/fish/brew.fish
index 22f10bacd34b4..d2ee34d0d2b4f 100644
--- a/completions/fish/brew.fish
+++ b/completions/fish/brew.fish
@@ -117,11 +117,11 @@ function __fish_brew_suggest_casks_all -d "Lists locally available casks"
 end
 
 function __fish_brew_suggest_casks_installed -d "Lists installed casks"
-    command ls -1 (brew --caskroom)
+    command ls -1 (brew --caskroom) 2>/dev/null
 end
 
 function __fish_brew_suggest_casks_outdated -d "Lists outdated casks with the information about potential upgrade"
-    brew outdated --cask --verbose \
+    brew outdated --cask --verbose 2>/dev/null \
         # replace first space with tab to make the following a description in the completions list:
         | string replace -r '\s' '\t'
 end