diff --git a/src/boot/efi/efi-string.h b/src/boot/efi/efi-string.h
index c25349c0e1..57899c978b 100644
--- a/src/boot/efi/efi-string.h
+++ b/src/boot/efi/efi-string.h
@@ -112,6 +112,13 @@ bool parse_number16(const char16_t *s, uint64_t *ret_u, const char16_t **ret_tai
 #  define memcmp __builtin_memcmp
 #  define memcpy __builtin_memcpy
 #  define memset __builtin_memset
+
+static inline void *mempcpy(void * restrict dest, const void * restrict src, size_t n) {
+        if (!dest || !src || n == 0)
+                return dest;
+        memcpy(dest, src, n);
+        return (uint8_t *) dest + n;
+}
 #endif
 
 /* The actual implementations of builtins with efi_ prefix so we can unit test them. */