diff --git a/include/asm-blackfin/config.h b/include/asm-blackfin/config.h
index fbfd598..0ae838a 100644
--- a/include/asm-blackfin/config.h
+++ b/include/asm-blackfin/config.h
@@ -92,7 +92,11 @@
 # define CONFIG_SYS_MAX_RAM_SIZE (CONFIG_MEM_SIZE * 1024 * 1024)
 #endif
 #ifndef CONFIG_SYS_MONITOR_BASE
-# define CONFIG_SYS_MONITOR_BASE (CONFIG_SYS_MAX_RAM_SIZE - CONFIG_SYS_MONITOR_LEN)
+# if CONFIG_SYS_MAX_RAM_SIZE
+#  define CONFIG_SYS_MONITOR_BASE (CONFIG_SYS_MAX_RAM_SIZE - CONFIG_SYS_MONITOR_LEN)
+# else
+#  define CONFIG_SYS_MONITOR_BASE 0
+# endif
 #endif
 #ifndef CONFIG_SYS_MALLOC_BASE
 # define CONFIG_SYS_MALLOC_BASE (CONFIG_SYS_MONITOR_BASE - CONFIG_SYS_MALLOC_LEN)
@@ -114,7 +118,8 @@
 #endif
 
 /* Check to make sure everything fits in external RAM */
-#if ((CONFIG_SYS_MONITOR_BASE + CONFIG_SYS_MONITOR_LEN) > CONFIG_SYS_MAX_RAM_SIZE)
+#if CONFIG_SYS_MAX_RAM_SIZE && \
+    ((CONFIG_SYS_MONITOR_BASE + CONFIG_SYS_MONITOR_LEN) > CONFIG_SYS_MAX_RAM_SIZE)
 # error Memory Map does not fit into configuration
 #endif