diff --git a/include/coap/address.h b/include/coap/address.h
index 05644423..426207ad 100644
--- a/include/coap/address.h
+++ b/include/coap/address.h
@@ -14,25 +14,9 @@
 #ifndef _COAP_ADDRESS_H_
 #define _COAP_ADDRESS_H_
 
-#ifdef HAVE_ASSERT_H
 #include <assert.h>
-#else
-#ifndef assert
-#warning "assertions are disabled"
-#  define assert(x)
-#endif
-#endif
-
-#include <string.h>
 #include <stdint.h>
-
-#ifdef HAVE_NETINET_IN_H
-#include <netinet/in.h>
-#endif
-
-#ifdef HAVE_NETINET_IN_H
-#include <sys/socket.h>
-#endif
+#include <string.h>
 
 #ifdef WITH_LWIP
 #include <lwip/ip_addr.h>
diff --git a/include/coap/coap_io.h b/include/coap/coap_io.h
index 65b66e07..3362d951 100644
--- a/include/coap/coap_io.h
+++ b/include/coap/coap_io.h
@@ -9,18 +9,8 @@
 #ifndef _COAP_IO_H_
 #define _COAP_IO_H_
 
-#ifdef HAVE_ASSERT_H
 #include <assert.h>
-#else
-#ifndef assert
-#warning "assertions are disabled"
-#  define assert(x)
-#endif
-#endif
-
-#ifdef HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
+#include <sys/types.h>
 
 #include "address.h"
 
diff --git a/include/coap/mem.h b/include/coap/mem.h
index e4ef73c1..6072ec07 100644
--- a/include/coap/mem.h
+++ b/include/coap/mem.h
@@ -9,9 +9,7 @@
 #ifndef _COAP_MEM_H_
 #define _COAP_MEM_H_
 
-#ifdef HAVE_STDLIB_H
 #include <stdlib.h>
-#endif
 
 #ifndef WITH_LWIP
 /**
diff --git a/include/coap/net.h b/include/coap/net.h
index 871c3286..f50c47c1 100644
--- a/include/coap/net.h
+++ b/include/coap/net.h
@@ -13,26 +13,11 @@
 extern "C" {
 #endif
 
-#ifdef HAVE_ASSERT_H
 #include <assert.h>
-#else
-#ifndef assert
-#warning "assertions are disabled"
-#  define assert(x)
-#endif
-#endif
-
 #include <stdlib.h>
 #include <string.h>
-#ifdef HAVE_NETINET_IN_H
-#include <netinet/in.h>
-#endif
-#ifdef HAVE_TIME_H
-#include <time.h>
-#endif
-#ifdef HAVE_SYS_TIME_H
 #include <sys/time.h>
-#endif
+#include <time.h>
 
 #ifdef WITH_LWIP
 #include <lwip/ip_addr.h>
diff --git a/include/coap/resource.h b/include/coap/resource.h
index e6a55ec4..e2c00ac3 100644
--- a/include/coap/resource.h
+++ b/include/coap/resource.h
@@ -14,9 +14,7 @@
 #ifndef _COAP_RESOURCE_H_
 #define _COAP_RESOURCE_H_
 
-#if defined(HAVE_ASSERT_H) && !defined(assert)
 # include <assert.h>
-#endif
 
 #ifndef COAP_RESOURCE_CHECK_TIME
 /** The interval in seconds to check if resources have changed. */