diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index d3d1ef031..38dc9f8c0 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -58,10 +58,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ macos-14, macos-15, macos-15-intel, macos-26, macos-26-intel, ubuntu-24.04 ]
+        os: [ macos-14, macos-15, macos-15-intel, macos-26, macos-26-intel, ubuntu-24.04, ubuntu-26.04-arm ]
         compiler: [ gcc ]
         version: [ 12, 13, 14, 15, 16 ]
-        extra_flags: [ -g ]
 
         include:
           - os: ubuntu-24.04
@@ -91,6 +90,11 @@ jobs:
             version: 22
 
           # https://hub.docker.com/r/phhargrove/llvm-flang/tags
+          - os: ubuntu-24.04
+            compiler: clang
+            version: 23
+            conduits: *ubuntu_conduits
+            container: phhargrove/llvm-flang:23.1.0_rc2-latest
           - os: ubuntu-24.04
             compiler: clang
             version: 22
@@ -146,8 +150,10 @@ jobs:
     env:
       COMPILER_VERSION: ${{ matrix.version }}
       CC: ${{ matrix.compiler }}
-      CFLAGS: ${{ matrix.extra_flags }}
-      CONFIGURE_ARGS: --disable-mpi-compat --enable-rpath --enable-debug ${{ inputs.configure_args }}
+      CFLAGS: ${{ matrix.cflags }}
+      CXXFLAGS: ${{ matrix.cxxflags }}
+      LDFLAGS: ${{ matrix.ldflags }}
+      CONFIGURE_ARGS: --disable-mpi-compat --enable-rpath --enable-debug --enable-smp --enable-udp ${{ inputs.configure_args }}
       GASNET_BACKTRACE: 1
       GASNET_SPAWN_VERBOSE: 1
       GASNET_VERBOSEENV: 1
@@ -174,8 +180,8 @@ jobs:
         sudo apt update
         #sudo apt list -a 'gcc-*'
         sudo apt install -y build-essential autoconf2.69 automake
-        if [[ ${COMPILER_VERSION} -lt 15 ]] ; then
-          sudo apt install -y gcc-${COMPILER_VERSION}
+        if [[ ${COMPILER_VERSION} -lt 15 ]] || type -p gcc-${COMPILER_VERSION} ; then
+          sudo apt install -y gcc-${COMPILER_VERSION} g++-${COMPILER_VERSION}
         else
           curl -L https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh -o install-homebrew.sh
           chmod +x install-homebrew.sh
diff --git a/other/amudp/amudp_spmd.cpp b/other/amudp/amudp_spmd.cpp
index 5810eb69f..241d27295 100644
--- a/other/amudp/amudp_spmd.cpp
+++ b/other/amudp/amudp_spmd.cpp
@@ -924,6 +924,7 @@ extern int AMUDP_SPMDStartup(int *argc, char ***argv,
                 int result;
                 do {
                   int status = 0;
+                  errno = 0; // ensure success doesn't output garbage in verbose mode
                   result = waitpid(-1, &status, 0);
                   if (result == -1 && errno == ECHILD) break;
                   if (!AMX_SilentMode) AMX_Info("result=%i status=%i errno=%s",result,status,strerror(errno));