diff --git a/scripts/run-kani.sh b/scripts/run-kani.sh
index 72c08b984ead9..3fae40a625641 100755
--- a/scripts/run-kani.sh
+++ b/scripts/run-kani.sh
@@ -162,6 +162,12 @@ build_kani() {
         if [[ "$os_name" == "Linux" ]]; then
             ./scripts/setup/ubuntu/install_deps.sh
         elif [[ "$os_name" == "Darwin" ]]; then
+            # Homebrew 6.0+ refuses to load formulae from third-party taps
+            # unless they are explicitly trusted, which breaks the
+            # `brew tap diffblue/cbmc` in the pinned Kani's install_cbmc.sh.
+            # Trust the tap first (no-op on older Homebrew). Mirrors
+            # model-checking/kani#4785.
+            brew trust diffblue/cbmc 2>/dev/null || true
             ./scripts/setup/macos/install_deps.sh
         else
             echo "Unknown operating system"