diff -r 0db02ab1457c -r bf5d647f939d make/project.xml
--- a/make/project.xml	Wed Dec 17 20:13:08 2025 +0100
+++ b/make/project.xml	Thu Dec 18 12:11:30 2025 +0100
@@ -99,10 +99,15 @@
     </dependency>
 
     <dependency name="memrchr">
-        <test>$TOOLCHAIN_CC $CFLAGS $LDFLAGS -o /dev/null -D_GNU_SOURCE make/test_memrchr.c</test>
+        <test>$TOOLCHAIN_CC $CFLAGS $LDFLAGS -o /dev/null make/test_memrchr.c</test>
         <cflags>-DWITH_MEMRCHR</cflags>
     </dependency>
 
+    <dependency name="qsort_r">
+        <test>$TOOLCHAIN_CC $CFLAGS $LDFLAGS -o /dev/null make/test_qsort_r.c</test>
+        <cflags>-DWITH_QSORT_R</cflags>
+    </dependency>
+
     <target>
         <feature name="api-docs">
             <dependencies>doxygen</dependencies>
@@ -120,9 +125,6 @@
             <desc>address sanitizer</desc>
             <dependencies>asan</dependencies>
         </feature>
-        <feature name="memrchr" default="true">
-            <dependencies>memrchr</dependencies>
-        </feature>
         <feature name="cxx-tests" default="true">
             <dependencies>cxx</dependencies>
             <desc>the check-cxx makefile target</desc>
@@ -138,5 +140,11 @@
                 <define name="CX_NO_SZMUL_BUILTIN"/>
             </disabled>
         </feature>
+        <feature name="memrchr" default="true">
+            <dependencies>memrchr</dependencies>
+        </feature>
+        <feature name="qsort_r" default="true">
+            <dependencies>qsort_r</dependencies>
+        </feature>
     </target>
 </project>