diff --git a/lib/threads/libjxl_threads.pc.in b/lib/threads/libjxl_threads.pc.in
index dfbaa3f..2c7bfe8 100644
--- a/lib/threads/libjxl_threads.pc.in
+++ b/lib/threads/libjxl_threads.pc.in
@@ -8,6 +8,6 @@ Description: JPEG XL multi-thread runner using std::threads.
 Version: @JPEGXL_LIBRARY_VERSION@
 @JPEGXL_REQUIRES_TYPE@: @JPEGXL_THREADS_LIBRARY_REQUIRES@
 Libs: -L${libdir} -ljxl_threads
-Libs.private: -lm
+Libs.private: -lm @PKGCONFIG_CXX_LIB@
 Cflags: -I${includedir}
 Cflags.private: -DJXL_THREADS_STATIC_DEFINE