diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 5bf6f54a..06988ffd 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -23,7 +23,7 @@ cmake_minimum_required(VERSION 3.5)
 
 project(tinydtls-tests)
 
-add_executable(dtls-server dtls-server.c dtls_ciphers_util.c)
+add_executable(dtls-server dtls-server.c)
 target_link_libraries(dtls-server LINK_PUBLIC tinydtls)
 target_compile_options(dtls-server PUBLIC -Wall -DTEST_INCLUDE -DDTLSv12 -DWITH_SHA256)
 if(${WARNING_TO_ERROR})
@@ -37,7 +37,7 @@ if(${WARNING_TO_ERROR})
     target_compile_options(ccm-test PUBLIC -Werror)
 endif()
 
-add_executable(dtls-client dtls-client.c dtls_ciphers_util.c)
+add_executable(dtls-client dtls-client.c)
 target_link_libraries(dtls-client LINK_PUBLIC tinydtls)
 target_compile_options(dtls-client PUBLIC -Wall -DTEST_INCLUDE -DDTLSv12 -DWITH_SHA256)
 if(${WARNING_TO_ERROR})
diff --git a/tests/dtls-client.c b/tests/dtls-client.c
index 6c927c5e..d586b70a 100644
--- a/tests/dtls-client.c
+++ b/tests/dtls-client.c
@@ -568,3 +568,4 @@ main(int argc, char **argv) {
   exit(0);
 }
 
+#include "dtls_ciphers_util.c"
diff --git a/tests/dtls-server.c b/tests/dtls-server.c
index 6f2b87d0..a0404831 100644
--- a/tests/dtls-server.c
+++ b/tests/dtls-server.c
@@ -428,3 +428,6 @@ main(int argc, char **argv) {
   dtls_free_context(the_context);
   exit(0);
 }
+
+#include "dtls_ciphers_util.c"
+
diff --git a/tests/dtls_ciphers_util.c b/tests/dtls_ciphers_util.c
index 2fc749bd..915e6969 100644
--- a/tests/dtls_ciphers_util.c
+++ b/tests/dtls_ciphers_util.c
@@ -41,7 +41,7 @@ static const struct cipher_entry map[] = {
 static dtls_cipher_t ciphers_table[ARRAY_LENGTH] = { TLS_NULL_WITH_NULL_NULL };
 
 static dtls_cipher_t find_cipher_suite(const char *arg) {
-  for (int index=0; index < ARRAY_LENGTH - 1; ++index) {
+  for (size_t index=0; index < ARRAY_LENGTH - 1; ++index) {
     size_t len = strlen(map[index].name);
     if (strncmp(arg, map[index].name, len) == 0 && (arg[len] == 0 || arg[len] == SEP)) {
       return map[index].cipher;
@@ -51,7 +51,7 @@ static dtls_cipher_t find_cipher_suite(const char *arg) {
 }
 
 static void add_cipher_suite(dtls_cipher_t cipher) {
-  for (int index=0; index < ARRAY_LENGTH - 1; ++index) {
+  for (size_t index=0; index < ARRAY_LENGTH - 1; ++index) {
     if (ciphers_table[index] == cipher) {
       return;
     }