diff --git a/scheduler/pthread.c b/scheduler/pthread.c
index fb1755586d2..9af6b3154b1 100644
--- a/scheduler/pthread.c
+++ b/scheduler/pthread.c
@@ -14,6 +14,7 @@
 #include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "winbase.h"
 #include "thread.h"
diff --git a/scheduler/synchro.c b/scheduler/synchro.c
index 91f47efb7af..45159eec839 100644
--- a/scheduler/synchro.c
+++ b/scheduler/synchro.c
@@ -9,6 +9,7 @@
 #include <signal.h>
 #include <sys/time.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "file.h"  /* for DOSFS_UnixTimeToFileTime */
 #include "thread.h"
diff --git a/server/atom.c b/server/atom.c
index 55fc6b7f23f..63be7b48b75 100644
--- a/server/atom.c
+++ b/server/atom.c
@@ -8,6 +8,7 @@
 #include <assert.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <string.h>
 
 #include "unicode.h"
 #include "request.h"
diff --git a/tools/winebuild/spec32.c b/tools/winebuild/spec32.c
index 694a99b4bdc..d550960641d 100644
--- a/tools/winebuild/spec32.c
+++ b/tools/winebuild/spec32.c
@@ -11,6 +11,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <unistd.h>
+#include <string.h>
 
 #include "config.h"
 #include "winbase.h"
diff --git a/tools/wmc/mcl.c b/tools/wmc/mcl.c
index 55fd27be213..65a8c9c71eb 100644
--- a/tools/wmc/mcl.c
+++ b/tools/wmc/mcl.c
@@ -8,6 +8,7 @@
 #include <stdlib.h>
 #include <ctype.h>
 #include <assert.h>
+#include <string.h>
 
 #include "config.h"