diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4899a06..c59e357 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -303,6 +303,10 @@ set(prefix          "${CMAKE_INSTALL_PREFIX}")
 set(exec_prefix     "${CMAKE_INSTALL_PREFIX}")
 set(libdir          "${CMAKE_INSTALL_FULL_LIBDIR}")
 set(includedir      "${CMAKE_INSTALL_FULL_INCLUDEDIR}")
+set(boost_cflags "")
+foreach(dir IN LISTS Boost_INCLUDE_DIRS)
+  set(boost_cflags "${boost_cflags} -I${dir}")
+endforeach()
 set(VERSION         "${PACKAGE_VERSION}")
 # For init scripts and systemd service file (in contrib/)
 set(bindir          "${CMAKE_INSTALL_FULL_BINDIR}")
diff --git a/lib/libnghttp2_asio.pc.in b/lib/libnghttp2_asio.pc.in
index ec4fbbb..c51f26c 100644
--- a/lib/libnghttp2_asio.pc.in
+++ b/lib/libnghttp2_asio.pc.in
@@ -30,4 +30,4 @@ Description: HTTP/2 C++ library
 URL: https://github.com/tatsuhiro-t/nghttp2
 Version: @VERSION@
 Libs: -L${libdir} -lnghttp2_asio
-Cflags: -I${includedir}
+Cflags: -I${includedir}@boost_cflags@