diff --git a/src/crypto/sha1extra.c b/src/crypto/sha1extra.c
index 74445e9d..12b29a6a 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 89bb36fd..38fd199f 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 780738e7..c88f556e 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 0a94df07..8bb3e5aa 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>