diff --git a/scripts/build-toolchains.sh b/scripts/build-toolchains.sh
index 611f50e01a..19fa524e44 100755
--- a/scripts/build-toolchains.sh
+++ b/scripts/build-toolchains.sh
@@ -6,7 +6,9 @@
 set -e
 set -o pipefail
 
-DIR="$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")"
+# If BASH_SOURCE is undefined, we may be running under zsh, in that case
+# provide a zsh-compatible alternative
+DIR="$(dirname "$(readlink -f "${BASH_SOURCE[0]:-${(%):-%x}}")")"
 CHIPYARD_DIR="$(dirname "$DIR")"
 
 usage() {
diff --git a/scripts/init-submodules-no-riscv-tools-nolog.sh b/scripts/init-submodules-no-riscv-tools-nolog.sh
index 0039d9df15..2d2e920cef 100755
--- a/scripts/init-submodules-no-riscv-tools-nolog.sh
+++ b/scripts/init-submodules-no-riscv-tools-nolog.sh
@@ -17,7 +17,9 @@ if [ "$MINGIT" != "$(echo -e "$MINGIT\n$MYGIT" | sort -V | head -n1)" ]; then
   false
 fi
 
-DIR="$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")"
+# If BASH_SOURCE is undefined we may be running under zsh, in that case
+# provide a zsh-compatible alternative
+DIR="$(dirname "$(readlink -f "${BASH_SOURCE[0]:-${(%):-%x}}")")"
 CHIPYARD_DIR="$(dirname "$DIR")"
 
 cd "$CHIPYARD_DIR"