diff --git a/common/common-manylinux_2_34.crosstool b/common/common-manylinux_2_34.crosstool
index b7f96a6..728c6ec 100644
--- a/common/common-manylinux_2_34.crosstool
+++ b/common/common-manylinux_2_34.crosstool
@@ -52,6 +52,13 @@ COPY \
   manylinux_2_34-aarch64/crosstool-ng.config \
   /dockcross/
 
+# Copy sys/sdt.h to a clean include directory to avoid pulling in all of
+# /usr/include (which causes __float128 conflicts on AlmaLinux 9 when
+# cross-compiling for aarch64).
+RUN mkdir -p /opt/ct-ng-includes/sys && \
+  cp /usr/include/sys/sdt.h /opt/ct-ng-includes/sys/ && \
+  cp /usr/include/sys/sdt-config.h /opt/ct-ng-includes/sys/
+
 # Build and install the toolchain, cleaning up artifacts afterwards.
 RUN \
   mkdir /dockcross/crosstool && \
diff --git a/manylinux_2_34-aarch64/crosstool-ng.config b/manylinux_2_34-aarch64/crosstool-ng.config
index 69bda96..8af2642 100644
--- a/manylinux_2_34-aarch64/crosstool-ng.config
+++ b/manylinux_2_34-aarch64/crosstool-ng.config
@@ -562,7 +562,7 @@ CT_GCC_4_9_or_later=y
 CT_CC_GCC_ENABLE_PLUGINS=y
 CT_CC_GCC_GOLD=y
 CT_CC_GCC_HAS_LIBMPX=y
-CT_CC_GCC_ENABLE_CXX_FLAGS="-I/usr/include -fpermissive"
+CT_CC_GCC_ENABLE_CXX_FLAGS="-I/opt/ct-ng-includes -fpermissive"
 CT_CC_GCC_CORE_EXTRA_CONFIG_ARRAY="--disable-gcov"
 CT_CC_GCC_EXTRA_CONFIG_ARRAY=""
 CT_CC_GCC_STATIC_LIBSTDCXX=y