diff --git a/.cirrus.yml b/.cirrus.yml
index ffbd820710527..699811954433a 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -135,7 +135,9 @@ task:
   ##   - rm /tmp/.com.apple.dt.CommandLineTools.installondemand.in-progress
   ##
   brew_valgrind_pre_script:
-    - brew update
+    # Reinstall brew. We could do `brew update` instead but that often fails.
+    - /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/uninstall.sh)"
+    - /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
     - brew config
     - brew tap LouisBrunner/valgrind
     # Fetch valgrind source but don't build it yet.