diff --git a/src/util/reallocarray.h b/src/util/reallocarray.h
index d072c60ba3f..602013919bc 100644
--- a/src/util/reallocarray.h
+++ b/src/util/reallocarray.h
@@ -27,6 +27,7 @@
 #if !defined(HAVE_REALLOCARRAY)
 
 #include <stdlib.h> // size_t
+#include <errno.h>
 
 #ifdef __cplusplus
 extern "C" {