diff --git a/libgimp/tests/libgimp-run-c-test.sh b/libgimp/tests/libgimp-run-c-test.sh
index eda39c0a97..674cd6351e 100644
--- a/libgimp/tests/libgimp-run-c-test.sh
+++ b/libgimp/tests/libgimp-run-c-test.sh
@@ -10,4 +10,4 @@ cmd="import os; import sys; sys.path.insert(0, '$SRC_DIR'); from pygimp.utils im
 cmd="$cmd proc = Gimp.get_pdb().lookup_procedure('$TEST_NAME'); gimp_c_assert('$TEST_FILE', 'Test PDB procedure does not exist: {}'.format('$TEST_NAME'), proc is not None);"
 cmd="$cmd result = proc.run(None);"
 cmd="$cmd print('SUCCESS') if result.index(0) == Gimp.PDBStatusType.SUCCESS else gimp_c_assert('$TEST_FILE', result.index(1), False);"
-echo "$cmd" | "$GIMP_EXE" -nis --batch-interpreter "python-fu-eval" -b - --quit
+echo "$cmd" | python3 "$GIMP_EXE" -nis --batch-interpreter "python-fu-eval" -b - --quit
diff --git a/libgimp/tests/libgimp-run-python-test.sh b/libgimp/tests/libgimp-run-python-test.sh
index 6973bbf334..d22b88f90f 100644
--- a/libgimp/tests/libgimp-run-python-test.sh
+++ b/libgimp/tests/libgimp-run-python-test.sh
@@ -24,4 +24,4 @@ fi
 header="import os; import sys; sys.path.insert(0, '$SRC_DIR'); from pygimp.utils import gimp_assert;"
 header="$header import pygimp.utils; pygimp.utils.gimp_test_filename = '$TEST_FILE'"
 
-(echo "$header" && tail -n +2 "$TEST_FILE") | "$GIMP_EXE" -nis --batch-interpreter "python-fu-eval" -b - --quit
+(echo "$header" && tail -n +2 "$TEST_FILE") | python3 "$GIMP_EXE" -nis --batch-interpreter "python-fu-eval" -b - --quit
diff --git a/meson.build b/meson.build
index 68d787c820..0223808918 100644
--- a/meson.build
+++ b/meson.build
@@ -2053,7 +2053,7 @@ else
   gimp_exe_depends = []
 endif
 
-gimp_exe = find_program('tools'/'in-build-gimp.sh')
+gimp_exe = find_program('tools'/'in-build-gimp.py')
 
 ################################################################################
 # Subdirs: part 2
diff --git a/tools/in-build-gimp.py b/tools/in-build-gimp.py
new file mode 100644
index 0000000000..c7e7f55e5f
--- /dev/null
+++ b/tools/in-build-gimp.py
@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+import os
+import random
+import shutil
+import string
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+try:
+    GIMP_GLOBAL_BUILD_ROOT = os.environ.get("GIMP_GLOBAL_BUILD_ROOT", ".")
+
+    suffix = ''.join(random.choices(string.ascii_lowercase + string.digits, k=6))
+    GIMP3_DIRECTORY = os.path.join(GIMP_GLOBAL_BUILD_ROOT, f".GIMP3-build-config-{suffix}")
+    os.makedirs(GIMP3_DIRECTORY, mode=0o700, exist_ok=False)
+    os.environ["GIMP3_DIRECTORY"] = GIMP3_DIRECTORY
+    print(f"INFO: temporary GIMP configuration directory: {GIMP3_DIRECTORY}")
+
+    if "GIMP_TEMP_UPDATE_RPATH" in os.environ:
+        # Earlier code used to set DYLD_LIBRARY_PATH environment variable instead, but
+        # it didn't work on contributor's builds because of System Integrity
+        # Protection (SIP), though it did work in the CI.            
+        for binary in os.environ["GIMP_TEMP_UPDATE_RPATH"].split(":"):
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimp", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpbase", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpcolor", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpconfig", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpmath", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpmodule", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpthumb", binary], check=True)
+            subprocess.run(["install_name_tool", "-add_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpwidgets", binary], check=True)
+
+    if "GIMP_DEBUG_SELF" in os.environ and shutil.which("gdb"):
+        print(f"RUNNING: gdb --batch -x {os.environ['GIMP_GLOBAL_SOURCE_ROOT']}/tools/debug-in-build-gimp.py --args {os.environ['GIMP_SELF_IN_BUILD']} {' '.join(sys.argv[1:])}")
+        subprocess.run(["gdb","--return-child-result","--batch","-x",f"{os.environ['GIMP_GLOBAL_SOURCE_ROOT']}/tools/debug-in-build-gimp.py","--args", os.environ["GIMP_SELF_IN_BUILD"]] + sys.argv[1:], stdin=sys.stdin, check=True)
+    else:
+        print(f"RUNNING: {os.environ['GIMP_SELF_IN_BUILD']} {' '.join(sys.argv[1:])}")
+        subprocess.run([os.environ["GIMP_SELF_IN_BUILD"]] + sys.argv[1:],stdin=sys.stdin, check=True)
+
+    if "GIMP_TEMP_UPDATE_RPATH" in os.environ:
+        for binary in os.environ["GIMP_TEMP_UPDATE_RPATH"].split(":"):
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimp", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpbase", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpcolor", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpconfig", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpmath", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpmodule", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpthumb", binary], check=True)
+            subprocess.run(["install_name_tool", "-delete_rpath", f"{GIMP_GLOBAL_BUILD_ROOT}/libgimpwidgets", binary], check=True)
+
+    # Clean-up the temporary config directory after each usage, yet making sure we
+    # don't get tricked by weird redirections or anything of the sort. In particular
+    # we check that this is a directory with user permission, not a symlink, and
+    # that it's inside inside the project build's root.
+    if "GIMP3_DIRECTORY" in os.environ and os.path.isdir(GIMP3_DIRECTORY):
+        if os.path.islink(GIMP3_DIRECTORY):
+            print(f"ERROR: $GIMP3_DIRECTORY ({GIMP3_DIRECTORY}) should not be a symlink.")
+            sys.exit(1)
+        used_dir_prefix = str(Path(GIMP3_DIRECTORY).resolve().as_posix())[:-6]
+        tmpl_dir_prefix = f"{Path(os.environ['GIMP_GLOBAL_BUILD_ROOT']).resolve().as_posix()}/.GIMP3-build-config-"
+        if used_dir_prefix != tmpl_dir_prefix:
+            print(f"ERROR: $GIMP3_DIRECTORY ({GIMP3_DIRECTORY}) should be under the build directory with a specific prefix.")
+            print(f'       "{used_dir_prefix}" != "{tmpl_dir_prefix}"')
+            sys.exit(1)
+        print(f"INFO: Running: shutil.rmtree({GIMP3_DIRECTORY})")
+        shutil.rmtree(GIMP3_DIRECTORY)
+    elif not os.access(GIMP3_DIRECTORY, os.W_OK):
+        print(f"ERROR: $GIMP3_DIRECTORY ({GIMP3_DIRECTORY}) does not belong to the user")
+        sys.exit(1)
+    else:
+        print(f"ERROR: $GIMP3_DIRECTORY ({GIMP3_DIRECTORY}) is not a directory")
+        sys.exit(1)
+
+except subprocess.CalledProcessError as e:
+    print(f"Command failed with exit code {e.returncode}: {e.cmd}")
+    sys.exit(e.returncode)
+except Exception as e:
+    print(f"Error: {str(e)}")
+    sys.exit(1)
diff --git a/tools/in-build-gimp.sh b/tools/in-build-gimp.sh
deleted file mode 100755
index 878e351ccc..0000000000
--- a/tools/in-build-gimp.sh
+++ /dev/null
@@ -1,83 +0,0 @@
-#!/bin/sh
-
-set -e
-
-export GIMP3_DIRECTORY=$(mktemp -d ${GIMP_GLOBAL_BUILD_ROOT}/.GIMP3-build-config-XXXXXX)
-echo INFO: temporary GIMP configuration directory: $GIMP3_DIRECTORY
-
-if [ -n "$GIMP_TEMP_UPDATE_RPATH" ]; then
-  # Earlier code used to set DYLD_LIBRARY_PATH environment variable instead, but
-  # it didn't work on contributor's builds because of System Integrity
-  # Protection (SIP), though it did work in the CI.
-  export IFS=":"
-  for bin in $GIMP_TEMP_UPDATE_RPATH;
-  do
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimp $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpbase $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpcolor $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpconfig $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpmath $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpmodule $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpthumb $bin
-    install_name_tool -add_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpwidgets $bin
-  done;
-  unset IFS
-fi
-
-if [ -n "$GIMP_DEBUG_SELF" ] && command -v gdb; then
-  echo RUNNING: cat /dev/stdin "|" gdb --batch -x "$GIMP_GLOBAL_SOURCE_ROOT/tools/debug-in-build-gimp.py" --args $GIMP_SELF_IN_BUILD "$@"
-  cat /dev/stdin | gdb --return-child-result --batch -x "$GIMP_GLOBAL_SOURCE_ROOT/tools/debug-in-build-gimp.py" --args $GIMP_SELF_IN_BUILD "$@"
-else
-  echo RUNNING: cat /dev/stdin "|" $GIMP_SELF_IN_BUILD "$@"
-  cat /dev/stdin | $GIMP_SELF_IN_BUILD "$@"
-fi
-
-if [ -n "$GIMP_TEMP_UPDATE_RPATH" ]; then
-  export IFS=":"
-  for bin in $GIMP_TEMP_UPDATE_RPATH;
-  do
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimp $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpbase $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpcolor $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpconfig $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpmath $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpmodule $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpthumb $bin
-    install_name_tool -delete_rpath ${GIMP_GLOBAL_BUILD_ROOT}/libgimpwidgets $bin
-  done;
-  unset IFS
-fi
-
-# Clean-up the temporary config directory after each usage, yet making sure we
-# don't get tricked by weird redirections or anything of the sort. In particular
-# we check that this is a directory with user permission, not a symlink, and
-# that it's inside inside the project build's root.
-if [ -n "$GIMP3_DIRECTORY" ] && [ -d "$GIMP3_DIRECTORY" ] && [ -O "$GIMP3_DIRECTORY" ]; then
-  if [ -L "$GIMP3_DIRECTORY" ]; then
-    echo "ERROR: \$GIMP3_DIRECTORY ($GIMP3_DIRECTORY) should not be a symlink."
-    exit 1
-  fi
-  used_dir_prefix=$(realpath "$GIMP3_DIRECTORY")
-  used_dir_prefix=${used_dir_prefix%??????}
-  tmpl_dir_prefix=$(realpath "$GIMP_GLOBAL_BUILD_ROOT")/.GIMP3-build-config-
-  if [ "$used_dir_prefix" != "$tmpl_dir_prefix" ]; then
-    echo "ERROR: \$GIMP3_DIRECTORY ($GIMP3_DIRECTORY) should be under the build directory with a specific prefix."
-    echo "       \"$used_dir_prefix\" != \"$tmpl_dir_prefix\""
-    exit 1
-  fi
-  RM_OPTIONS=""
-  if [ -z "$GIMP_TEMP_UPDATE_RPATH" ]; then
-    # macOS doesn't have the additional security options.
-    # Testing for other OS or environments (apparently these options are
-    # not on busybox for instance).
-    echo "INFO: Testing if rm supports --preserve-root"
-    rm --help | grep no-preserve-root && RM_OPTIONS="--no-preserve-root"
-    echo "INFO: Testing if rm supports --one-file-system"
-    rm --help | grep one-file-system && RM_OPTIONS="$RM_OPTIONS --one-file-system"
-  fi
-  echo INFO: Running: rm -fr $RM_OPTIONS \"$GIMP3_DIRECTORY\"
-  rm -fr $RM_OPTIONS "$GIMP3_DIRECTORY"
-else
-  echo "ERROR: \$GIMP3_DIRECTORY ($GIMP3_DIRECTORY) is not a directory or does not belong to the user"
-  exit 1
-fi