diff --git a/src/core/memp.c b/src/core/memp.c
index 15852439..3dbbec11 100644
--- a/src/core/memp.c
+++ b/src/core/memp.c
@@ -130,7 +130,7 @@ static struct memp *memp_tab[MEMP_MAX];
 #endif /* MEMP_MEM_MALLOC */
 
 /** This array holds the element sizes of each pool. */
-#if !MEM_USE_POOLS && !MEMP_MEM_MALLOC
+#if !MEM_USE_POOLS && !MEMP_MEM_MALLOC && !MEMP_USE_CUSTOM_POOLS
 static
 #endif
 const u16_t memp_sizes[MEMP_MAX] = {
diff --git a/src/include/lwip/memp.h b/src/include/lwip/memp.h
index 8bcc43a1..405c1094 100644
--- a/src/include/lwip/memp.h
+++ b/src/include/lwip/memp.h
@@ -75,9 +75,9 @@ typedef enum {
 #define MEMP_POOL_LAST   ((memp_t) MEMP_POOL_HELPER_LAST)
 #endif /* MEM_USE_POOLS */
 
-#if MEMP_MEM_MALLOC || MEM_USE_POOLS
+#if MEMP_MEM_MALLOC || MEM_USE_POOLS || MEMP_USE_CUSTOM_POOLS
 extern const u16_t memp_sizes[MEMP_MAX];
-#endif /* MEMP_MEM_MALLOC || MEM_USE_POOLS */
+#endif /* MEMP_MEM_MALLOC || MEM_USE_POOLS || MEMP_USE_CUSTOM_POOLS */
 
 #if MEMP_MEM_MALLOC