diff --git a/.gitignore b/.gitignore
index e50a283..1f36a17 100644
--- a/.gitignore
+++ b/.gitignore
@@ -94,3 +94,7 @@
 # Benchmarking input and output
 /bench/data
 /bench/work
+
+# AmigaOS packaging output
+dist/
+bld-*/
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 44b696b..361e39a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -126,9 +126,45 @@ if (AMIGA)
         endif()
     elseif ($ENV{CROSS_PFX} STREQUAL "ppc-amigaos")
         set(AMIGA_PPC ON)
-        message(STATUS "Building for PowerPC AmigaOS")
+        if (NOT DEFINED PPC_CRT)
+            set(PPC_CRT "newlib")
+        endif()
+        set(PPC_CRT "${PPC_CRT}" CACHE STRING "ppc-amigaos C runtime: newlib, clib2 or clib4")
+        set_property(CACHE PPC_CRT PROPERTY STRINGS newlib clib2 clib4)
+        if (NOT PPC_CRT STREQUAL "newlib" AND
+            NOT PPC_CRT STREQUAL "clib2" AND
+            NOT PPC_CRT STREQUAL "clib4")
+            message(FATAL_ERROR "PPC_CRT must be newlib, clib2 or clib4 (got: ${PPC_CRT})")
+        endif()
+        if (NOT PPC_CRT STREQUAL "newlib")
+            set(CMAKE_C_FLAGS       "${CMAKE_C_FLAGS} -mcrt=${PPC_CRT}")
+        endif()
+        message(STATUS "Building for PowerPC AmigaOS using CRT: ${PPC_CRT}")
     elseif($ENV{CROSS_PFX} STREQUAL "ppc-morphos")
         set(MORPHOS ON)
+        if (NOT DEFINED MORPHOS_CLIB)
+            set(MORPHOS_CLIB "default")
+        endif()
+        set(MORPHOS_CLIB "${MORPHOS_CLIB}" CACHE STRING "MorphOS C library: default or libnix")
+        set_property(CACHE MORPHOS_CLIB PROPERTY STRINGS default libnix)
+        if (NOT MORPHOS_CLIB STREQUAL "default" AND NOT MORPHOS_CLIB STREQUAL "libnix")
+            message(FATAL_ERROR "MORPHOS_CLIB must be default or libnix (got: ${MORPHOS_CLIB})")
+        endif()
+        option(MORPHOS_BASEREL32 "MorphOS: build with -mbaserel32" OFF)
+        if (MORPHOS_CLIB STREQUAL "libnix")
+            # Same situation as the -noixemul path below: libnix's headers
+            # disagree with the ixemul ones about va_list, so the varargs
+            # helpers in debug.c trip -Wincompatible-pointer-types.
+            set(DISABLE_WERROR ON)
+            set(CMAKE_C_FLAGS       "${CMAKE_C_FLAGS} -Wno-incompatible-pointer-types")
+        endif()
+        if (MORPHOS_CLIB STREQUAL "libnix")
+            set(CMAKE_C_FLAGS       "${CMAKE_C_FLAGS} -mclib=libnix")
+        endif()
+        if (MORPHOS_BASEREL32)
+            set(CMAKE_C_FLAGS       "${CMAKE_C_FLAGS} -mbaserel32")
+        endif()
+        message(STATUS "Building for PowerPC MorphOS using clib: ${MORPHOS_CLIB}, baserel32: ${MORPHOS_BASEREL32}")
         if (NOIXEMUL)
             message(STATUS "Building for PowerPC MorphOS without ixemul")
             set(DISABLE_WERROR ON)
diff --git a/README.md b/README.md
index 098c8a6..5d33b21 100644
--- a/README.md
+++ b/README.md
@@ -346,6 +346,13 @@ make
 
 libjson-c.a will get created in the build directory.
 
+Select the C runtime with `-DPPC_CRT=`: `newlib` (default), `clib2` or `clib4`.
+Anything other than `newlib` is passed to the compiler as `-mcrt=<value>`.
+
+```
+cmake -DPPC_CRT=clib4 ..
+```
+
 ### To build for PowerPC MorphOS:
 
 ```
@@ -363,6 +370,72 @@ If you are making an application that absolutely requires ixemul, then remove th
 
 libjson-c.a will get created in the build directory.
 
+Two further options apply to MorphOS:
+
+* `-DMORPHOS_CLIB=` selects `default` (ixemul) or `libnix` (passed as
+  `-mclib=libnix`). That is the same multilib `-noixemul` selects, and is the
+  self-contained ABI -- an ixemul build needs `ixemul.library` on the target.
+* `-DMORPHOS_BASEREL32=ON` adds `-mbaserel32`.
+
+```
+cmake -DMORPHOS_CLIB=libnix ..
+cmake -DMORPHOS_BASEREL32=ON ..
+```
+
+### Building and packaging every variant
+
+Two scripts at the repository root build the whole matrix across all three
+systems, so you do not have to drive the container by hand.
+
+* `build-amiga-sdk.sh [OS ...]` — builds every variant and installs
+  `libjson-c.a` plus the `json-c/` headers into an SDK tree. The location comes
+  from `$AMIGA_SDK` (default `/opt/amiga`); either a `<target>/` or an
+  AmigaSDK-gcc-style `amigaos3/sdk/<target>/` layout is accepted, and an OS
+  whose subdirectory is absent is skipped rather than failing.
+* `package-amiga.sh [OS ...]` — builds the same matrix into a staging tree and
+  produces `dist/json-c.lha` for distribution.
+
+Both default to `AmigaOS3 AmigaOS4 MorphOS`, and both take the variant list
+from the same table in `build-amiga-sdk.sh`, so they cannot disagree. 22
+libraries are built in total: 15 for AmigaOS 3 (newlib, libnix and clib2, each
+across the five multilib slots), 3 for AmigaOS 4 (newlib, clib2, clib4) and 4
+for MorphOS (ixemul and native, each with and without `-mbaserel32`).
+
+Which of them actually *link* is a separate question from whether they build,
+and was checked by compiling a program against each one:
+
+| target | links |
+|--------|-------|
+| AmigaOS 3, libnix | all 5 slots |
+| AmigaOS 3, clib2 | `lib/libm020/` and `lib/libb32/libm020/` only |
+| AmigaOS 3, newlib | none -- the m68k newlib tree has no `gettimeofday()` |
+| AmigaOS 4 | all 3 (newlib, clib2, clib4) |
+| MorphOS | all 4 slots |
+
+The clib2 failures are inside clib2 itself: its 68000 multilib provides no
+`strtoll`/`strtoull`, and 16-bit `-fbaserel` overflows with *truncated to fit:
+DREL16* once json-c's data is added -- `-fbaserel32` has no 64 KB limit. Link
+with `-ljson-c -lm` after your own objects, and add `-lunix` for clib2.
+
+The archive is laid out with the readme at the root and one directory per
+system, each following the compiler's own layout so it can be copied straight
+over an SDK:
+
+```
+json-c.readme
+json-c/AmigaOS3/{include,lib,...}/     plus libnix/ and clib2/ subtrees
+json-c/AmigaOS4/{include,lib,lib/clib2,lib/clib4}/
+json-c/MorphOS/{include,lib,lib/libb32,lib/libnix}/
+```
+
+Note that m68k and PPC lay their C runtimes out differently, and the variant
+table follows each. On m68k a runtime is a separate tree (`libnix/`, `clib2/`),
+each with its own `include/` and `lib/`. On PPC a runtime is a multilib *slot*
+beneath a single shared `lib/`: `-mcrt=clib4` searches `<target>/lib/clib4/`
+and takes headers from `<target>/include/`. This was read off
+`-print-search-dirs` rather than assumed, because installing to the wrong one
+produces a library the compiler silently never finds.
+
 <a name="linking"></a>
 Linking to `libjson-c`
 ----------------------
diff --git a/build-amiga-sdk.sh b/build-amiga-sdk.sh
new file mode 100755
index 0000000..835edda
--- /dev/null
+++ b/build-amiga-sdk.sh
@@ -0,0 +1,111 @@
+#!/usr/bin/env bash
+# Cross-build json-c for Amiga systems across every multilib slot and install
+# the archives plus headers into an SDK tree.
+#
+#   ./build-amiga-sdk.sh [OS ...]        # default: AmigaOS3 AmigaOS4 MorphOS
+#
+# SDK location comes from $AMIGA_SDK (default /opt/amiga).
+set -uo pipefail
+
+SDK=${AMIGA_SDK:-/opt/amiga}
+cd "$(dirname "$0")"
+ROOT=$PWD
+OSES=("$@"); [[ ${#OSES[@]} -eq 0 ]] && OSES=(AmigaOS3 AmigaOS4 MorphOS)
+
+# os | image tag | sdk subdir
+os_image() { case "$1" in
+  AmigaOS3) echo "sacredbanana/amiga-compiler:m68k-amigaos m68k-amigaos" ;;
+  AmigaOS4) echo "sacredbanana/amiga-compiler:ppc-amigaos ppc-amigaos" ;;
+  MorphOS)  echo "sacredbanana/amiga-compiler:ppc-morphos ppc-morphos" ;;
+  *) return 1 ;;
+esac; }
+
+# Where an AmigaSDK-gcc-style checkout keeps each system's target tree.
+os_sdkdir() { case "$1" in
+  AmigaOS3) echo "amigaos3/sdk" ;;
+  AmigaOS4) echo "amigaos4/sdk" ;;
+  MorphOS)  echo "morphos/sdk" ;;
+  *) return 1 ;;
+esac; }
+
+# Per-OS variant table: "tree|slot|cmake args"
+variants_AmigaOS3=(
+  "libnix|.|-DM68K_CRT=nix20 -DM68K_CPU=68000 -DM68K_BASEREL=off"
+  "libnix|libm020|-DM68K_CRT=nix20 -DM68K_CPU=68020 -DM68K_BASEREL=off"
+  "libnix|libb|-DM68K_CRT=nix20 -DM68K_CPU=68000 -DM68K_BASEREL=baserel"
+  "libnix|libb/libm020|-DM68K_CRT=nix20 -DM68K_CPU=68020 -DM68K_BASEREL=baserel"
+  "libnix|libb32/libm020|-DM68K_CRT=nix20 -DM68K_CPU=68020 -DM68K_BASEREL=baserel32"
+  ".|.|-DM68K_CRT=newlib -DM68K_CPU=68000 -DM68K_BASEREL=off"
+  ".|libm020|-DM68K_CRT=newlib -DM68K_CPU=68020 -DM68K_BASEREL=off"
+  ".|libb|-DM68K_CRT=newlib -DM68K_CPU=68000 -DM68K_BASEREL=baserel"
+  ".|libb/libm020|-DM68K_CRT=newlib -DM68K_CPU=68020 -DM68K_BASEREL=baserel"
+  ".|libb32/libm020|-DM68K_CRT=newlib -DM68K_CPU=68020 -DM68K_BASEREL=baserel32"
+  "clib2|.|-DM68K_CRT=clib2 -DM68K_CPU=68000 -DM68K_BASEREL=off"
+  "clib2|libm020|-DM68K_CRT=clib2 -DM68K_CPU=68020 -DM68K_BASEREL=off"
+  "clib2|libb|-DM68K_CRT=clib2 -DM68K_CPU=68000 -DM68K_BASEREL=baserel"
+  "clib2|libb/libm020|-DM68K_CRT=clib2 -DM68K_CPU=68020 -DM68K_BASEREL=baserel"
+  "clib2|libb32/libm020|-DM68K_CRT=clib2 -DM68K_CPU=68020 -DM68K_BASEREL=baserel32"
+)
+# Unlike m68k, where each C runtime is its own tree (libnix/, clib2/), the PPC
+# toolchains make the runtime a multilib SLOT under lib/, with headers coming
+# from the shared <target>/include/. Verified with -print-search-dirs:
+#   ppc-amigaos  -mcrt=clib2  -> <target>/lib/clib2/
+#   ppc-amigaos  -mcrt=clib4  -> <target>/lib/clib4/
+#   ppc-morphos  -mclib=libnix-> <target>/lib/libnix/
+#   ppc-morphos  -mbaserel32  -> <target>/lib/libb32/
+variants_AmigaOS4=(
+  ".|.|-DPPC_CRT=newlib"
+  ".|clib2|-DPPC_CRT=clib2"
+  ".|clib4|-DPPC_CRT=clib4"
+)
+# MORPHOS_CLIB=libnix (-mclib=libnix) and NOIXEMUL (-noixemul) select the same
+# multilib; it is the self-contained ABI, needing no ixemul.library on target.
+variants_MorphOS=(
+  ".|.|"
+  ".|libb32|-DMORPHOS_BASEREL32=ON"
+  ".|libnix|-DMORPHOS_CLIB=libnix"
+  ".|libb32/libnix|-DMORPHOS_CLIB=libnix -DMORPHOS_BASEREL32=ON"
+)
+
+# $1 out-dir-for-libs  $2 out-dir-for-headers  $3.. OS list
+ok=0; fail=0; failed=()
+for os in "${OSES[@]}"; do
+  read -r image sdksub <<<"$(os_image "$os")" || { echo "skip: unknown OS $os"; continue; }
+  # /opt/amiga keeps the target tree directly under <target>/, while an
+  # AmigaSDK-gcc checkout nests it under <os>/sdk/<target>. Accept either.
+  osdir=$(os_sdkdir "$os")
+  if   [[ -d $SDK/$sdksub ]];        then SDKROOT=$SDK/$sdksub
+  elif [[ -d $SDK/$osdir/$sdksub ]]; then SDKROOT=$SDK/$osdir/$sdksub
+  else echo "skip $os: neither $SDK/$sdksub nor $SDK/$osdir/$sdksub"; continue; fi
+
+  eval "vars=(\"\${variants_$os[@]}\")"
+  for v in "${vars[@]}"; do
+    IFS='|' read -r tree slot cargs <<<"$v"
+    bdir="bld-$os-$(echo "$tree$slot$cargs" | tr -c 'A-Za-z0-9' '-' | cut -c1-40)"
+    printf '  %-9s %-7s %-16s ' "$os" "$tree" "$slot"
+    if ! docker run --rm -v "$ROOT":/work -e USER="$(id -u)" -e GROUP="$(id -g)" "$image" sh -c "
+        set -e
+        rm -rf /work/$bdir && mkdir -p /work/$bdir && cd /work/$bdir
+        cmake $cargs -DCMAKE_BUILD_TYPE=Release -DBUILD_APPS=NO \
+              -DCMAKE_INSTALL_PREFIX=/work/$bdir/inst .. >cmake.log 2>&1
+        make -j\$(nproc) json-c >make.log 2>&1
+        make install >install.log 2>&1
+      " 2>/dev/null; then
+      echo "BUILD FAILED (logs in $bdir)"; fail=$((fail+1)); failed+=("$os/$tree/$slot"); continue
+    fi
+    lib=$bdir/libjson-c.a
+    [[ -f $lib ]] || lib=$bdir/inst/lib/libjson-c.a
+    [[ -f $lib ]] || { echo "no libjson-c.a"; fail=$((fail+1)); failed+=("$os/$tree/$slot"); continue; }
+
+    base=$SDKROOT; [[ $tree != "." ]] && base=$SDKROOT/$tree
+    dest=$base/lib; [[ $slot != "." ]] && dest=$base/lib/$slot
+    mkdir -p "$dest" "$base/include"
+    cp "$lib" "$dest/libjson-c.a"
+    cp -a "$bdir/inst/include/json-c" "$base/include/"
+    echo "ok"; ok=$((ok+1)); rm -rf "$bdir"
+  done
+done
+echo
+echo "built+installed: $ok   failed: $fail"
+((fail)) && { printf 'failures: %s\n' "${failed[*]}"; exit 1; }
+exit 0
diff --git a/json-c.readme b/json-c.readme
new file mode 100644
index 0000000..67b447e
--- /dev/null
+++ b/json-c.readme
@@ -0,0 +1,110 @@
+Short:         JSON parser and generator library (static libs + headers)
+Author:        Michael Clark, Eric Haszlakiewicz et al.
+Uploader:      Cameron Armstrong <cameronscottarmstrong@gmail.com>
+Type:          dev/lib
+Version:       0.19.99
+Architecture:  m68k-amigaos >= 2.0; ppc-amigaos; ppc-morphos
+Distribution:  Aminet
+Requires:      an Amiga gcc cross compiler
+
+json-c implements a reference-counted object model for JSON, a parser that
+builds it from text, and a serialiser that writes it back out. This archive
+contains static libraries and public headers for Amiga development.
+
+    https://github.com/json-c/json-c
+
+
+Contents
+
+    json-c.readme                    this file
+    json-c/AmigaOS3/...              m68k AmigaOS libraries and headers
+    json-c/AmigaOS4/...              ppc-amigaos libraries and headers
+    json-c/MorphOS/...               ppc-morphos libraries and headers
+
+    Under each OS directory the trees follow the compiler's own layout, so
+    they can be copied straight over an existing SDK, e.g.
+
+        cp -a json-c/AmigaOS3/* /opt/amiga/m68k-amigaos/
+
+    AmigaOS3 ships one set per C runtime -- newlib at the top level, plus
+    libnix/ and clib2/ -- and within each, one library per multilib:
+
+        lib/                   68000, absolute addressing
+        lib/libm020/           68020, absolute addressing
+        lib/libb/              68000, -fbaserel
+        lib/libb/libm020/      68020, -fbaserel
+        lib/libb32/libm020/    68020, -fbaserel32
+
+    On PPC a C runtime is not a separate tree but a multilib slot beneath one
+    shared lib/, with headers in the single shared include/:
+
+        AmigaOS4    lib/               newlib
+                    lib/clib2/         clib2
+                    lib/clib4/         clib4
+
+        MorphOS     lib/               ixemul
+                    lib/libb32/        ixemul, -mbaserel32
+                    lib/libnix/        native C library (-noixemul)
+                    lib/libb32/libnix/ native C library, -mbaserel32
+
+    -mclib=libnix and -noixemul select the same MorphOS multilib. That ABI is
+    the self-contained one -- an ixemul build needs ixemul.library on the
+    target -- so prefer lib/libnix/ for new code.
+
+
+Usage
+
+    #include <json-c/json.h>
+
+    struct json_object *o = json_tokener_parse("{\"a\":1}");
+    printf("%s\n", json_object_to_json_string(o));
+    json_object_put(o);
+
+    Link with -ljson-c -lm, after your own objects on the command line. For
+    clib2 add -lunix as well, since clib2 keeps its POSIX layer there.
+
+
+Which variants link
+
+    Verified by compiling the snippet above against each shipped library.
+
+    AmigaOS3  libnix    all 5 slots link.
+
+              clib2     lib/libm020/ and lib/libb32/libm020/ link. The other
+                        three fail inside clib2 itself: its 68000 multilib has
+                        no strtoll()/strtoull(), and 16-bit -fbaserel overflows
+                        with "truncated to fit: DREL16" once json-c's data is
+                        added. -fbaserel32 has no such limit.
+
+              newlib    builds, but does not link: the m68k newlib tree has no
+                        gettimeofday(). The libraries are shipped anyway, since
+                        that is a gap in the SDK rather than in json-c and a
+                        newlib with gettimeofday() implemented would link.
+
+    AmigaOS4  all three (newlib, clib2, clib4) link.
+
+    MorphOS   all four slots link.
+
+
+A note on base-relative addressing (AmigaOS3)
+
+    A base-relative library addresses its globals through a4, which the
+    program's startup code sets up once. Only link the libb/ or libb32/
+    variants into a program that is itself base-relative AND that marks every
+    function the OS calls back into (BOOPSI/MUI dispatchers, struct Hook
+    entries, interrupt servers) with __saveds. The m68k SDI_hook.h macros set
+    up register arguments but do not add __saveds, so this is easy to get
+    wrong, and the failure mode is intermittent memory corruption rather than
+    a clean error -- libnix keeps malloc's heap state in a4-relative storage.
+
+    Conversely a non-base-relative library built at -O1 or above may use a4 as
+    a scratch register, which is harmless in a non-base-relative program but
+    corrupts the base pointer of one that is.
+
+    Match the variant to the program. If in doubt, use the plain lib/ or
+    lib/libm020/ builds.
+
+
+Licence
+
+    MIT; see COPYING in the source distribution.
diff --git a/package-amiga.sh b/package-amiga.sh
new file mode 100755
index 0000000..075991f
--- /dev/null
+++ b/package-amiga.sh
@@ -0,0 +1,62 @@
+#!/usr/bin/env bash
+# Build every json-c variant for the requested Amiga systems and package them
+# into dist/json-c.lha.
+#
+#   ./package-amiga.sh [OS ...]        # default: all three
+#
+# Archive layout:
+#     json-c.readme          at the archive root
+#     json-c/AmigaOS3/...    per-OS libraries and headers
+#     json-c/AmigaOS4/...
+#     json-c/MorphOS/...
+set -uo pipefail
+
+cd "$(dirname "$0")"
+ROOT=$PWD
+DIST=$ROOT/dist
+STAGE=$DIST/stage
+OSES=("$@"); [[ ${#OSES[@]} -eq 0 ]] && OSES=(AmigaOS3 AmigaOS4 MorphOS)
+
+command -v lha >/dev/null || { echo "error: lha not found on PATH" >&2; exit 1; }
+
+# Build straight into the staging tree by pointing AMIGA_SDK at it: the build
+# script's SDK layout ($SDK/<target>) is the same shape we want per OS, so each
+# OS gets staged under its own directory.
+rm -rf "$DIST"; mkdir -p "$STAGE/json-c"
+cp "$ROOT/json-c.readme" "$STAGE/json-c.readme"
+
+built=()
+for os in "${OSES[@]}"; do
+  case "$os" in
+    AmigaOS3) sub=m68k-amigaos ;;
+    AmigaOS4) sub=ppc-amigaos ;;
+    MorphOS)  sub=ppc-morphos ;;
+    *) echo "skip: unknown OS $os"; continue ;;
+  esac
+  tmp=$DIST/sdk-$os
+  mkdir -p "$tmp/$sub"
+  echo "=== $os ==="
+  # Stage whatever landed even if some variants failed -- a single unsupported
+  # multilib should not drop the whole OS from the archive.
+  AMIGA_SDK="$tmp" ./build-amiga-sdk.sh "$os" || echo "  ($os: some variants failed, see above)"
+  if [[ -n $(find "$tmp/$sub" -name 'libjson-c.a' -print -quit 2>/dev/null) ]]; then
+    mkdir -p "$STAGE/json-c/$os"
+    cp -a "$tmp/$sub/." "$STAGE/json-c/$os/"
+    built+=("$os")
+  else
+    echo "  $os: nothing built, omitted from the archive"
+  fi
+  rm -rf "$tmp"
+done
+
+[[ ${#built[@]} -eq 0 ]] && { echo "nothing built"; exit 1; }
+
+# NOTE: build the archive from a clean staging tree with `lha -aq2`. Do NOT try
+# to refresh a single entry (e.g. the readme) in an existing archive with
+# `lha u` -- it APPENDS a second entry with the same name rather than replacing
+# it, and extraction then yields the stale copy.
+( cd "$STAGE" && lha -aq2 "$DIST/json-c.lha" * >/dev/null )
+rm -rf "$STAGE"
+echo
+echo "packaged: ${built[*]}"
+ls -la "$DIST"