diff --git a/postgres-types/src/lib.rs b/postgres-types/src/lib.rs
index 463e3dee..5c5a0d02 100644
--- a/postgres-types/src/lib.rs
+++ b/postgres-types/src/lib.rs
@@ -836,7 +836,7 @@ pub trait ToSql: fmt::Debug {
     ) -> Result<IsNull, Box<dyn Error + Sync + Send>>;
 
     /// Specify the encode format
-    fn encode_format(&self) -> Format {
+    fn encode_format(&self, _ty: &Type) -> Format {
         Format::Binary
     }
 }
@@ -868,8 +868,8 @@ where
         T::accepts(ty)
     }
 
-    fn encode_format(&self) -> Format {
-        (*self).encode_format()
+    fn encode_format(&self, ty: &Type) -> Format {
+        (*self).encode_format(ty)
     }
 
     to_sql_checked!();
@@ -891,9 +891,9 @@ impl<T: ToSql> ToSql for Option<T> {
         <T as ToSql>::accepts(ty)
     }
 
-    fn encode_format(&self) -> Format {
+    fn encode_format(&self, ty: &Type) -> Format {
         match self {
-            Some(ref val) => val.encode_format(),
+            Some(ref val) => val.encode_format(ty),
             None => Format::Binary,
         }
     }
diff --git a/tokio-postgres/src/query.rs b/tokio-postgres/src/query.rs
index f1593dbc..5f8cbf7c 100644
--- a/tokio-postgres/src/query.rs
+++ b/tokio-postgres/src/query.rs
@@ -156,16 +156,18 @@ where
     I: IntoIterator<Item = P>,
     I::IntoIter: ExactSizeIterator,
 {
+    let param_types = statement.params();
     let (param_formats, params): (Vec<_>, Vec<_>) = params
         .into_iter()
-        .map(|p| (p.borrow_to_sql().encode_format() as i16, p))
+        .zip(param_types.iter())
+        .map(|(p, ty)| (p.borrow_to_sql().encode_format(ty) as i16, p))
         .unzip();
     let params = params.into_iter();
 
     assert!(
-        statement.params().len() == params.len(),
+        param_types.len() == params.len(),
         "expected {} parameters but got {}",
-        statement.params().len(),
+        param_types.len(),
         params.len()
     );
 
@@ -174,7 +176,7 @@ where
         portal,
         statement.name(),
         param_formats,
-        params.zip(statement.params()).enumerate(),
+        params.zip(param_types).enumerate(),
         |(idx, (param, ty)), buf| match param.borrow_to_sql().to_sql_checked(ty, buf) {
             Ok(IsNull::No) => Ok(postgres_protocol::IsNull::No),
             Ok(IsNull::Yes) => Ok(postgres_protocol::IsNull::Yes),