diff --git a/roles/custom/matrix-synapse/defaults/main.yml b/roles/custom/matrix-synapse/defaults/main.yml
index edc956abf..ae5a0335f 100644
--- a/roles/custom/matrix-synapse/defaults/main.yml
+++ b/roles/custom/matrix-synapse/defaults/main.yml
@@ -552,11 +552,11 @@ matrix_synapse_event_cache_size: "100K"
 # - https://github.com/element-hq/synapse/issues/3939
 matrix_synapse_caches_global_factor: 10
 matrix_synapse_caches_expire_caches: true
-matrix_synapse_caches_cache_entry_ttl: 30m
-matrix_synapse_caches_sync_response_cache_duration: 2m
-matrix_synapse_caches_autotuning_max_cache_memory_usage: 2048M
-matrix_synapse_caches_autotuning_target_cache_memory_usage: 1024M
-matrix_synapse_caches_autotuning_min_cache_ttl: 5m
+matrix_synapse_caches_cache_entry_ttl: "30m"
+matrix_synapse_caches_sync_response_cache_duration: "2m"
+matrix_synapse_caches_autotuning_max_cache_memory_usage: "2048M"
+matrix_synapse_caches_autotuning_target_cache_memory_usage: "1024M"
+matrix_synapse_caches_autotuning_min_cache_ttl: "5m"
 
 # Controls whether Synapse will federate at all.
 # Disable this to completely isolate your server from the rest of the Matrix network.