diff --git a/block/file-posix.c b/block/file-posix.c
index 0d85123d0f..a845e2836f 100644
--- a/block/file-posix.c
+++ b/block/file-posix.c
@@ -110,6 +110,10 @@
 #include <sys/diskslice.h>
 #endif
 
+#ifdef EMSCRIPTEN
+#include <sys/ioctl.h>
+#endif
+
 /* OS X does not have O_DSYNC */
 #ifndef O_DSYNC
 #ifdef O_SYNC