diff --git a/postgrest/utils.py b/postgrest/utils.py
index 39dc1e29..d22beae0 100644
--- a/postgrest/utils.py
+++ b/postgrest/utils.py
@@ -5,6 +5,9 @@
 from httpx import AsyncClient  # noqa: F401
 from httpx import Client as BaseClient  # noqa: F401
 
+import json
+
+
 
 class SyncClient(BaseClient):
     def aclose(self) -> None:
@@ -12,7 +15,7 @@ def aclose(self) -> None:
 
 
 def sanitize_param(param: Any) -> str:
-    param_str = str(param)
+    param_str = json.dumps(param)
     reserved_chars = ",:()"
     if any(char in param_str for char in reserved_chars):
         return f'"{param_str}"'