diff --git a/src/crypto/sha1extra.c b/src/crypto/sha1extra.c
index 74445e9d1..12b29a6ac 100644
--- a/src/crypto/sha1extra.c
+++ b/src/crypto/sha1extra.c
@@ -18,6 +18,7 @@
 
 FILE_LICENCE ( GPL2_OR_LATER );
 
+#include <string.h>
 #include <ipxe/crypto.h>
 #include <ipxe/sha1.h>
 #include <ipxe/hmac.h>
diff --git a/src/net/80211/wpa_ccmp.c b/src/net/80211/wpa_ccmp.c
index 89bb36fd8..38fd199f8 100644
--- a/src/net/80211/wpa_ccmp.c
+++ b/src/net/80211/wpa_ccmp.c
@@ -18,6 +18,7 @@
 
 FILE_LICENCE ( GPL2_OR_LATER );
 
+#include <string.h>
 #include <ipxe/net80211.h>
 #include <ipxe/crypto.h>
 #include <ipxe/hmac.h>
diff --git a/src/net/80211/wpa_psk.c b/src/net/80211/wpa_psk.c
index 780738e79..c88f556e8 100644
--- a/src/net/80211/wpa_psk.c
+++ b/src/net/80211/wpa_psk.c
@@ -18,6 +18,7 @@
 
 FILE_LICENCE ( GPL2_OR_LATER );
 
+#include <string.h>
 #include <ipxe/net80211.h>
 #include <ipxe/sha1.h>
 #include <ipxe/wpa.h>
diff --git a/src/net/80211/wpa_tkip.c b/src/net/80211/wpa_tkip.c
index 0a94df07e..8bb3e5aaa 100644
--- a/src/net/80211/wpa_tkip.c
+++ b/src/net/80211/wpa_tkip.c
@@ -18,6 +18,7 @@
 
 FILE_LICENCE ( GPL2_OR_LATER );
 
+#include <string.h>
 #include <ipxe/net80211.h>
 #include <ipxe/crypto.h>
 #include <ipxe/hmac.h>