diff --git a/scripts/base_tools.sh b/scripts/base_tools.sh
index e8f8905..24ce07b 100755
--- a/scripts/base_tools.sh
+++ b/scripts/base_tools.sh
@@ -85,13 +85,6 @@ as_root apt-get install -y --no-install-recommends \
         traceroute \
         # end of list
 
-# public key for apt.llvm.org
-wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | as_root apt-key add -
-
-# for specific llvm/clang versions
-echo "deb http://apt.llvm.org/bullseye/ llvm-toolchain-bullseye-12 main" >> /etc/apt/sources.list
-as_root apt-get update -q
-
 # Install python dependencies
 # Upgrade pip first, then install setuptools (required for other pip packages)
 # Install some basic python tools
diff --git a/scripts/sel4.sh b/scripts/sel4.sh
index 7082474..1611e1d 100644
--- a/scripts/sel4.sh
+++ b/scripts/sel4.sh
@@ -71,7 +71,7 @@ as_root apt-get install -y --no-install-recommends \
     qemu-system-x86 \
     sloccount \
     u-boot-tools \
-    clang-12 \
+    clang-11 \
     g++-10 \
     g++-10-arm-linux-gnueabi \
     g++-10-arm-linux-gnueabihf \
@@ -80,7 +80,7 @@ as_root apt-get install -y --no-install-recommends \
     gcc-10-arm-linux-gnueabihf \
     gcc-10-base \
     gcc-riscv64-unknown-elf \
-    libclang-12-dev \
+    libclang-11-dev \
     qemu-system-arm \
     qemu-system-misc \
     $CROSS
@@ -144,12 +144,12 @@ if [ "$DESKTOP_MACHINE" = "no" ] ; then
         done
     done
 
-    # Ensure that clang-12 shows up as clang
+    # Ensure that clang-11 shows up as clang
     for compiler in clang \
                     clang++ \
                     # end of list
         do
-            as_root update-alternatives --install /usr/bin/"$compiler" "$compiler" "$(which "$compiler"-12)" 60 && \
+            as_root update-alternatives --install /usr/bin/"$compiler" "$compiler" "$(which "$compiler"-11)" 60 && \
             as_root update-alternatives --auto "$compiler"
     done
     # Do a quick check to make sure it works: