diff --git a/src/c/ffi/cdata.d b/src/c/ffi/cdata.d
index c6a89c92a..1a15e09e0 100644
--- a/src/c/ffi/cdata.d
+++ b/src/c/ffi/cdata.d
@@ -13,6 +13,7 @@
     See file '../Copyright' for full details.
 */
 
+#include <string.h>
 #include <ecl/ecl.h>
 #include <ecl/ecl-inl.h>
 
diff --git a/src/c/main.d b/src/c/main.d
index fffab2b76..a603ca02f 100644
--- a/src/c/main.d
+++ b/src/c/main.d
@@ -40,6 +40,7 @@
 #endif
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <ecl/cache.h>
 #include <ecl/internal.h>
 #include <ecl/ecl-inl.h>
diff --git a/src/c/num_rand.d b/src/c/num_rand.d
index 3e6d76f7d..f4a4cb519 100644
--- a/src/c/num_rand.d
+++ b/src/c/num_rand.d
@@ -21,6 +21,9 @@
 #include <stdlib.h>
 #include <ecl/internal.h>
 #include <fcntl.h>
+#if !defined(ECL_MS_WINDOWS_HOST)
+# include <unistd.h>
+#endif
 #if !defined(_MSC_VER) && !defined(__MINGW32__)
 # include <sys/stat.h>
 /* it isn't pulled in by fcntl.h */