diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index d8f0fd7..46e05db 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -1219,6 +1219,7 @@
 # Tests for Max Fragment Length extension
 
 run_test    "Max fragment length: not used, reference" \
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
             "$P_SRV debug_level=3" \
             "$P_CLI debug_level=3" \
             0 \
@@ -1229,6 +1230,7 @@
             -S "server hello, max_fragment_length extension" \
             -C "found max_fragment_length extension"
 
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 run_test    "Max fragment length: used by client" \
             "$P_SRV debug_level=3" \
             "$P_CLI debug_level=3 max_frag_len=4096" \
@@ -1240,6 +1242,7 @@
             -s "server hello, max_fragment_length extension" \
             -c "found max_fragment_length extension"
 
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 run_test    "Max fragment length: used by server" \
             "$P_SRV debug_level=3 max_frag_len=4096" \
             "$P_CLI debug_level=3" \
@@ -1251,6 +1254,7 @@
             -S "server hello, max_fragment_length extension" \
             -C "found max_fragment_length extension"
 
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 requires_gnutls
 run_test    "Max fragment length: gnutls server" \
             "$G_SRV" \
@@ -1260,6 +1264,7 @@
             -c "client hello, adding max_fragment_length extension" \
             -c "found max_fragment_length extension"
 
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 run_test    "Max fragment length: client, message just fits" \
             "$P_SRV debug_level=3" \
             "$P_CLI debug_level=3 max_frag_len=2048 request_size=2048" \
@@ -1273,6 +1278,7 @@
             -c "2048 bytes written in 1 fragments" \
             -s "2048 bytes read"
 
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 run_test    "Max fragment length: client, larger message" \
             "$P_SRV debug_level=3" \
             "$P_CLI debug_level=3 max_frag_len=2048 request_size=2345" \
@@ -1287,6 +1293,7 @@
             -s "2048 bytes read" \
             -s "297 bytes read"
 
+requires_config_enabled MBEDTLS_SSL_MAX_FRAGMENT_LENGTH
 run_test    "Max fragment length: DTLS client, larger message" \
             "$P_SRV debug_level=3 dtls=1" \
             "$P_CLI debug_level=3 dtls=1 max_frag_len=2048 request_size=2345" \