diff --git a/lib/isc/unix/meminfo.c b/lib/isc/unix/meminfo.c
index 07f0f7221b..fafed02d48 100644
--- a/lib/isc/unix/meminfo.c
+++ b/lib/isc/unix/meminfo.c
@@ -14,6 +14,8 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <config.h>
+
 #include <isc/meminfo.h>
 #include <unistd.h>
 #include <sys/sysctl.h>
diff --git a/lib/isc/win32/meminfo.c b/lib/isc/win32/meminfo.c
index aa259f228a..1ea7cde975 100644
--- a/lib/isc/win32/meminfo.c
+++ b/lib/isc/win32/meminfo.c
@@ -14,6 +14,8 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include <config.h>
+
 #include <windows.h>
 
 #include <isc/meminfo.h>
@@ -24,4 +26,4 @@ isc_meminfo_totalphys(void) {
 	status.dwLength = sizeof(statex);
 	GlobalMemoryStatusEx(&statex);
 	return ((size_t)statex.ullTotalPhys);
-}
\ No newline at end of file
+}