diff --git a/sourcehook/generate/sourcehook.h b/sourcehook/generate/sourcehook.h
index 1ba3e43..9d82f2a 100644
--- a/sourcehook/generate/sourcehook.h
+++ b/sourcehook/generate/sourcehook.h
@@ -86,6 +86,10 @@
 # define vsnprintf _vsnprintf
 #endif
 
+#if SH_SYS != SH_SYS_WIN32
+# include <unistd.h>
+#endif
+
 #define SH_PTRSIZE sizeof(void*)
 
 #include "FastDelegate.h"
diff --git a/sourcehook/generate/sourcehook.hxx b/sourcehook/generate/sourcehook.hxx
index d47a706..6a7fddb 100755
--- a/sourcehook/generate/sourcehook.hxx
+++ b/sourcehook/generate/sourcehook.hxx
@@ -86,6 +86,10 @@
 # define vsnprintf _vsnprintf
 #endif
 
+#if SH_SYS != SH_SYS_WIN32
+# include <unistd.h>
+#endif
+
 #define SH_PTRSIZE sizeof(void*)
 
 #include "FastDelegate.h"
diff --git a/sourcehook/sourcehook.h b/sourcehook/sourcehook.h
index 1ba3e43..9d82f2a 100644
--- a/sourcehook/sourcehook.h
+++ b/sourcehook/sourcehook.h
@@ -86,6 +86,10 @@
 # define vsnprintf _vsnprintf
 #endif
 
+#if SH_SYS != SH_SYS_WIN32
+# include <unistd.h>
+#endif
+
 #define SH_PTRSIZE sizeof(void*)
 
 #include "FastDelegate.h"