diff --git a/scripts/build-toolchains.sh b/scripts/build-toolchains.sh
index edc62696..611f50e0 100755
--- a/scripts/build-toolchains.sh
+++ b/scripts/build-toolchains.sh
@@ -165,6 +165,15 @@ if [ -z "$IGNOREQEMU" ] ; then
     # in the local config so that any further commands by the user have the rewrite. uggh. git, why you so ugly?
     git -C "$dir" config --local url.https://github.com/qemu.insteadOf https://git.qemu.org/git
     git -C "$dir" submodule foreach --recursive 'git config --local url.https://github.com/qemu.insteadOf https://git.qemu.org/git'
+
+    # check to see whether the rewrite rules are needed any more
+    # If you find git.qemu.org in any .gitmodules file below qemu, you still need them
+    # the /dev/null redirection in the submodule grepping is to quiet non-existance of further .gitmodules
+    ! grep -q 'git\.qemu\.org' "$dir/.gitmodules" && \
+    git -C "$dir" submodule foreach --quiet --recursive '! grep -q "git\.qemu\.org" .gitmodules 2>/dev/null' && \
+    echo "==>  PLEASE REMOVE qemu URL-REWRITING from scripts/build-toolchains.sh. It is no longer needed!" && exit 1
+
+    # now actually do the build
     SRCDIR="$(pwd)/toolchains" module_build qemu --prefix="${RISCV}" --target-list=riscv${XLEN}-softmmu
 fi