diff --git a/src/core/init.c b/src/core/init.c
index 31ad2c75..86adf1fb 100644
--- a/src/core/init.c
+++ b/src/core/init.c
@@ -98,10 +98,10 @@
   #error "If you want to use TCP, TCP_WND must fit in an u16_t, so, you have to reduce it in your lwipopts.h"
 #endif
 #if (LWIP_TCP && (TCP_SND_QUEUELEN > 0xffff))
-  #error If you want to use TCP, TCP_SND_QUEUELEN must fit in an u16_t, so, you have to reduce it in your lwipopts.h"
+  #error "If you want to use TCP, TCP_SND_QUEUELEN must fit in an u16_t, so, you have to reduce it in your lwipopts.h"
 #endif
 #if (LWIP_TCP && ((TCP_MAXRTX > 12) || (TCP_SYNMAXRTX > 12)))
-  #error If you want to use TCP, TCP_MAXRTX and TCP_SYNMAXRTX must less or equal to 12 (due to tcp_backoff table), so, you have to reduce them in your lwipopts.h"
+  #error "If you want to use TCP, TCP_MAXRTX and TCP_SYNMAXRTX must less or equal to 12 (due to tcp_backoff table), so, you have to reduce them in your lwipopts.h"
 #endif
 #if (LWIP_IGMP && (MEMP_NUM_IGMP_GROUP<=1))
   #error "If you want to use IGMP, you have to define MEMP_NUM_IGMP_GROUP>1 in your lwipopts.h"
@@ -121,7 +121,7 @@
 #if (!LWIP_NETCONN && LWIP_SOCKET)
   #error "If you want to use Socket API, you have to define LWIP_NETCONN=1 in your lwipopts.h"
 #endif
-#if (((!LWIP_DHCP) || (!LWIP_AUTOIP)) && DHCP_AUTOIP_COOP)
+#if (((!LWIP_DHCP) || (!LWIP_AUTOIP)) && LWIP_DHCP_AUTOIP_COOP)
   #error "If you want to use DHCP/AUTOIP cooperation mode, you have to define LWIP_DHCP=1 and LWIP_AUTOIP=1 in your lwipopts.h"
 #endif
 #if (((!LWIP_DHCP) || (!LWIP_ARP)) && DHCP_DOES_ARP_CHECK)
@@ -140,7 +140,7 @@
   #error "One and exactly one of LWIP_EVENT_API and LWIP_CALLBACK_API has to be enabled in lwipopts.h"
 #endif
 /* There must be sufficient timeouts, taking into account requirements of the subsystems. */
-#if ((NO_SYS==0) && (MEMP_NUM_SYS_TIMEOUT < (LWIP_TCP + IP_REASSEMBLY + LWIP_ARP + (2*LWIP_DHCP) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + LWIP_PPP)))
+#if ((NO_SYS==0) && (MEMP_NUM_SYS_TIMEOUT < (LWIP_TCP + IP_REASSEMBLY + LWIP_ARP + (2*LWIP_DHCP) + LWIP_AUTOIP + LWIP_IGMP + LWIP_DNS + PPP_SUPPORT)))
   #error "MEMP_NUM_SYS_TIMEOUT is too low to accomodate all required timeouts"
 #endif
 #if (IP_REASSEMBLY && (MEMP_NUM_REASSDATA > IP_REASS_MAX_PBUFS))