diff --git a/prism/defines.h b/prism/defines.h
index 8fa6a6a3d1..66c644939f 100644
--- a/prism/defines.h
+++ b/prism/defines.h
@@ -15,6 +15,7 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 
 /**
  * We want to be able to use the PRI* macros for printing out integers, but on
diff --git a/prism/util/pm_string.h b/prism/util/pm_string.h
index 758677b197..d6442fc608 100644
--- a/prism/util/pm_string.h
+++ b/prism/util/pm_string.h
@@ -21,7 +21,6 @@
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
-#include <unistd.h>
 #endif
 
 /**