diff --git a/tests/ssl-opt.sh b/tests/ssl-opt.sh
index 8d4313c5dc..2252feb925 100755
--- a/tests/ssl-opt.sh
+++ b/tests/ssl-opt.sh
@@ -12874,10 +12874,11 @@ not_with_valgrind # risk of non-mbedtls peer timing out
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
 run_test    "DTLS proxy: 3d, openssl server, fragmentation" \
             -p "$P_PXY drop=5 delay=5 duplicate=5 protect_hvr=1" \
-            "$O_NEXT_SRV -dtls1_2 -mtu 768" \
-            "$P_CLI dgram_packing=0 dtls=1 hs_timeout=500-60000 tickets=0" \
+            "$O_NEXT_SRV -dtls1_2 -mtu 256" \
+            "$P_CLI dgram_packing=0 dtls=1 debug_level=2 hs_timeout=500-60000 tickets=0" \
             0 \
-            -c "HTTP/1.0 200 OK"
+            -c "HTTP/1.0 200 OK" \
+            -c "Certificate handshake message has been buffered and reassembled"
 
 requires_openssl_next
 client_needs_more_time 8
@@ -12885,10 +12886,11 @@ not_with_valgrind # risk of non-mbedtls peer timing out
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
 run_test    "DTLS proxy: 3d, openssl server, fragmentation, nbio" \
             -p "$P_PXY drop=5 delay=5 duplicate=5 protect_hvr=1" \
-            "$O_NEXT_SRV -dtls1_2 -mtu 768" \
-            "$P_CLI dgram_packing=0 dtls=1 hs_timeout=500-60000 nbio=2 tickets=0" \
+            "$O_NEXT_SRV -dtls1_2 -mtu 256" \
+            "$P_CLI dgram_packing=0 dtls=1 debug_level=2 hs_timeout=500-60000 nbio=2 tickets=0" \
             0 \
-            -c "HTTP/1.0 200 OK"
+            -c "HTTP/1.0 200 OK" \
+            -c "Certificate handshake message has been buffered and reassembled"
 
 requires_gnutls
 client_needs_more_time 6
@@ -12909,10 +12911,11 @@ requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
 run_test    "DTLS proxy: 3d, gnutls server, fragmentation" \
             -p "$P_PXY drop=5 delay=5 duplicate=5" \
             "$G_NEXT_SRV -u --mtu 512" \
-            "$P_CLI dgram_packing=0 dtls=1 hs_timeout=500-60000" \
+            "$P_CLI dgram_packing=0 dtls=1 debug_level=2 hs_timeout=500-60000" \
             0 \
             -s "Extra-header:" \
-            -c "Extra-header:"
+            -c "Extra-header:" \
+            -c "Certificate handshake message has been buffered and reassembled"
 
 requires_gnutls_next
 client_needs_more_time 8
@@ -12921,10 +12924,11 @@ requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
 run_test    "DTLS proxy: 3d, gnutls server, fragmentation, nbio" \
             -p "$P_PXY drop=5 delay=5 duplicate=5" \
             "$G_NEXT_SRV -u --mtu 512" \
-            "$P_CLI dgram_packing=0 dtls=1 hs_timeout=500-60000 nbio=2" \
+            "$P_CLI dgram_packing=0 dtls=1 debug_level=2 hs_timeout=500-60000 nbio=2" \
             0 \
             -s "Extra-header:" \
-            -c "Extra-header:"
+            -c "Extra-header:" \
+            -c "Certificate handshake message has been buffered and reassembled"
 
 requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
 run_test    "export keys functionality" \