diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 9153fd1d..79b423d0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -182,8 +182,8 @@ jobs:
       - name: Install packages
         if: startsWith(matrix.os, 'ubuntu')
         run: |
-            SOURCE_KEYS=(${{join(matrix.source_keys, ' ')}})
-            SOURCES=(${{join(matrix.sources, ' ')}})
+            SOURCE_KEYS=("${{join(matrix.source_keys, '" "')}}")
+            SOURCES=("${{join(matrix.sources, '" "')}}")
             # Add this by default
             SOURCE_KEYS+=('http://keyserver.ubuntu.com/pks/lookup?op=get&search=0x1E9377A2BA9EF27F')
             SOURCES+=(ppa:ubuntu-toolchain-r/test)
diff --git a/ci/add-apt-keys.sh b/ci/add-apt-keys.sh
index 3c299ee5..3d3f71c6 100755
--- a/ci/add-apt-keys.sh
+++ b/ci/add-apt-keys.sh
@@ -1,12 +1,12 @@
 #!/bin/bash
 #
-# Copyright 2023 Alexander Grund
+# Copyright 2023-2024 Alexander Grund
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at
 #      http://www.boost.org/LICENSE_1_0.txt)
 #
 # Add APT keys
-# - Each argument should be a key URL
+# - Each argument should be a key URL or a key ID (0x...)
 # - $NET_RETRY_COUNT is the amount of retries attempted
 
 set -eu
@@ -16,9 +16,13 @@ function do_add_key
     key_url=$1
     # If a keyserver URL (e.g. http://keyserver.ubuntu.com/pks/lookup?op=get&search=0x1E9377A2BA9EF27F)
     # use the hash as the filename,
+    # if it is an ID, e.g. 0x1E9377A2BA9EF27F, use it as the filename, and http://keyserver.ubuntu.com/pks/lookup as the URL
     # else assume the URL contains a filename, e.g. https://apt.llvm.org/llvm-snapshot.gpg.key
     if [[ "$key_url" =~ .*keyserver.*search=0x([A-F0-9]+) ]]; then
         keyfilename="${BASH_REMATCH[1]}.key"
+    elif [[ $key_url =~ ^0x[A-F0-9]+$ ]]; then
+        keyfilename=${key_url#0x}.key
+        key_url="http://keyserver.ubuntu.com/pks/lookup?op=get&search=$key_url"
     else
         keyfilename=$(basename -s .key "$key_url")
     fi
@@ -30,5 +34,6 @@ function do_add_key
 }
 
 for key_url in "$@"; do
+    [[ -n $key_url ]] || continue
     do_add_key "$key_url"
 done
diff --git a/ci/add-apt-repositories.sh b/ci/add-apt-repositories.sh
index b5e5dce8..e31fb3ea 100755
--- a/ci/add-apt-repositories.sh
+++ b/ci/add-apt-repositories.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 #
-# Copyright 2023 Alexander Grund, Sam Darwin
+# Copyright 2023 Sam Darwin
+# Copyright 2023-2024 Alexander Grund
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at
 #      http://www.boost.org/LICENSE_1_0.txt)
@@ -28,5 +29,6 @@ function do_add_repository {
 }
 
 for repo_name in "$@"; do
+    [[ -n $repo_name ]] || continue
     do_add_repository "$repo_name"
 done