diff --git a/src/gen/gen-base.cpp b/src/gen/gen-base.cpp
index a13298c62..cb57a3aa0 100644
--- a/src/gen/gen-base.cpp
+++ b/src/gen/gen-base.cpp
@@ -99,6 +99,22 @@ pg_result_t gen_base_t::dbexec(params_t const &tmp_params,
     return connection().exec(sql_template.render());
 }
 
+void gen_base_t::dbprepare(std::string_view stmt, std::string const &templ)
+{
+    template_t sql_template{templ};
+    sql_template.set_params(get_params());
+    return connection().prepare(stmt, sql_template.render());
+}
+
+void gen_base_t::dbprepare(std::string_view stmt, params_t const &tmp_params,
+                           std::string const &templ)
+{
+    template_t sql_template{templ};
+    sql_template.set_params(get_params());
+    sql_template.set_params(tmp_params);
+    return connection().prepare(stmt, sql_template.render());
+}
+
 void gen_base_t::raster_table_preprocess(std::string const &table)
 {
     params_t tmp_params;
diff --git a/src/gen/gen-base.hpp b/src/gen/gen-base.hpp
index b935d7652..a9aae09c0 100644
--- a/src/gen/gen-base.hpp
+++ b/src/gen/gen-base.hpp
@@ -101,6 +101,11 @@ class gen_base_t
 
     pg_result_t dbexec(params_t const &tmp_params, std::string const &templ);
 
+    void dbprepare(std::string_view stmt, std::string const &templ);
+
+    void dbprepare(std::string_view stmt, params_t const &tmp_params,
+                   std::string const &templ);
+
     void raster_table_preprocess(std::string const &table);
 
     void raster_table_postprocess(std::string const &table);
diff --git a/src/gen/gen-discrete-isolation.cpp b/src/gen/gen-discrete-isolation.cpp
index 6c8ca8a55..952f0c0d6 100644
--- a/src/gen/gen-discrete-isolation.cpp
+++ b/src/gen/gen-discrete-isolation.cpp
@@ -132,9 +132,9 @@ FROM {src} WHERE {importance_column} > 0
     timer(m_timer_reorder).stop();
 
     log_gen("Writing results to destination table...");
-    dbexec("PREPARE update (int, real, int4, int8) AS"
-           " UPDATE {src} SET dirank = $1, discr_iso = $2, irank = $3"
-           " WHERE {id_column} = $4");
+    dbprepare("update", "UPDATE {src} SET dirank = $1::int,"
+                        " discr_iso = $2::real, irank = $3::int4"
+                        " WHERE {id_column} = $4::int8");
 
     timer(m_timer_write).start();
     connection().exec("BEGIN");
diff --git a/src/gen/gen-rivers.cpp b/src/gen/gen-rivers.cpp
index 0f7e8d1c8..a1b445e09 100644
--- a/src/gen/gen-rivers.cpp
+++ b/src/gen/gen-rivers.cpp
@@ -334,9 +334,8 @@ SELECT "{id_column}", "{width_column}", "{name_column}", "{geom_column}"
     }
 
     log_gen("Writing results to destination table...");
-    dbexec("PREPARE ins (int8, real, text, geometry) AS"
-           " INSERT INTO {dest} ({id_column}, width, name, geom)"
-           " VALUES ($1, $2, $3, $4)");
+    dbprepare("ins", "INSERT INTO {dest} ({id_column}, width, name, geom)"
+                     " VALUES ($1::int8, $2::real, $3::text, $4::geometry)");
 
     timer(m_timer_write).start();
     connection().exec("BEGIN");
diff --git a/src/gen/gen-tile-builtup.cpp b/src/gen/gen-tile-builtup.cpp
index e075bb8a9..234a2dc21 100644
--- a/src/gen/gen-tile-builtup.cpp
+++ b/src/gen/gen-tile-builtup.cpp
@@ -127,11 +127,10 @@ CREATE TABLE IF NOT EXISTS "{}" (
     }
 
     if (params->get_bool("make_valid")) {
-        params->set(
-            "geom_sql",
-            "(ST_Dump(ST_CollectionExtract(ST_MakeValid($1), 3))).geom");
+        params->set("geom_sql", "(ST_Dump(ST_CollectionExtract(ST_MakeValid("
+                                "$1::geometry), 3))).geom");
     } else {
-        params->set("geom_sql", "$1");
+        params->set("geom_sql", "$1::geometry");
     }
 
     if ((m_image_extent & (m_image_extent - 1)) != 0) {
@@ -154,28 +153,24 @@ CREATE TABLE IF NOT EXISTS "{}" (
     auto const schema = get_params().get_string("schema");
     for (auto const &src_table : m_source_tables) {
         params_t tmp_params;
-        tmp_params.set("N", std::to_string(n++));
         tmp_params.set("SRC", qualified_name(schema, src_table));
 
-        dbexec(tmp_params, R"(
-PREPARE get_geoms_{N} (real, real, real, real) AS
- SELECT "{geom_column}", '' AS param
+        dbprepare(fmt::format("get_geoms_{}", n++), tmp_params, R"(
+SELECT "{geom_column}", '' AS param
  FROM {SRC}
- WHERE "{geom_column}" && ST_MakeEnvelope($1, $2, $3, $4, 3857)
+ WHERE "{geom_column}" && ST_MakeEnvelope($1::real, $2::real, $3::real, $4::real, 3857)
 )");
     }
 
     if (m_has_area_column) {
-        dbexec(R"(
-PREPARE insert_geoms (geometry, int, int) AS
- INSERT INTO {dest} ("{geom_column}", x, y, "{area_column}")
- VALUES ({geom_sql}, $2, $3, $4)
+        dbprepare("insert_geoms", R"(
+INSERT INTO {dest} ("{geom_column}", x, y, "{area_column}")
+ VALUES ({geom_sql}, $2::int, $3::int, $4::real)
 )");
     } else {
-        dbexec(R"(
-PREPARE insert_geoms (geometry, int, int) AS
- INSERT INTO {dest} ("{geom_column}", x, y)
- VALUES ({geom_sql}, $2, $3)
+        dbprepare("insert_geoms", R"(
+INSERT INTO {dest} ("{geom_column}", x, y)
+ VALUES ({geom_sql}, $2::int, $3::int)
 )");
     }
 }
diff --git a/src/gen/gen-tile-raster.cpp b/src/gen/gen-tile-raster.cpp
index 4771b9d6d..2f945bbbc 100644
--- a/src/gen/gen-tile-raster.cpp
+++ b/src/gen/gen-tile-raster.cpp
@@ -116,11 +116,10 @@ CREATE TABLE IF NOT EXISTS "{}" (
     }
 
     if (get_params().get_bool("make_valid")) {
-        params->set(
-            "geom_sql",
-            "(ST_Dump(ST_CollectionExtract(ST_MakeValid($1), 3))).geom");
+        params->set("geom_sql", "(ST_Dump(ST_CollectionExtract("
+                                " ST_MakeValid($1::geometry), 3))).geom");
     } else {
-        params->set("geom_sql", "$1");
+        params->set("geom_sql", "$1::geometry");
     }
 
     if ((m_image_extent & (m_image_extent - 1)) != 0) {
@@ -142,26 +141,24 @@ CREATE TABLE IF NOT EXISTS "{}" (
     std::string prepare;
     if (with_group_by()) {
         prepare = R"(
-PREPARE get_geoms (real, real, real, real) AS
- SELECT "{geom_column}", "{group_by_column}"
+SELECT "{geom_column}", "{group_by_column}"
  FROM {src}
- WHERE "{geom_column}" && ST_MakeEnvelope($1, $2, $3, $4, 3857)
+ WHERE "{geom_column}" &&
+       ST_MakeEnvelope($1::real, $2::real, $3::real, $4::real, 3857)
 )";
-        dbexec(R"(
-PREPARE insert_geoms (geometry, int, int, text) AS
- INSERT INTO {dest} ("{geom_column}", x, y, "{group_by_column}")
- VALUES ({geom_sql}, $2, $3, $4)
+        dbprepare("insert_geoms", R"(
+INSERT INTO {dest} ("{geom_column}", x, y, "{group_by_column}")
+ VALUES ({geom_sql}, $2::int, $3::int, $4::text)
 )");
     } else {
         prepare = R"(
-PREPARE get_geoms (real, real, real, real) AS
- SELECT "{geom_column}", NULL AS param
+SELECT "{geom_column}", NULL AS param
  FROM {src}
- WHERE "{geom_column}" && ST_MakeEnvelope($1, $2, $3, $4, 3857)
+ WHERE "{geom_column}" &&
+       ST_MakeEnvelope($1::real, $2::real, $3::real, $4::real, 3857)
 )";
-        dbexec(R"(
-PREPARE insert_geoms (geometry, int, int, text) AS
- INSERT INTO {dest} ("{geom_column}", x, y) VALUES ({geom_sql}, $2, $3)
+        dbprepare("insert_geoms", R"(
+INSERT INTO {dest} ("{geom_column}", x, y) VALUES ({geom_sql}, $2::int, $3::int)
 )");
     }
 
@@ -169,7 +166,7 @@ PREPARE insert_geoms (geometry, int, int, text) AS
         prepare.append(fmt::format(" AND ({})", where_condition));
     }
 
-    dbexec(prepare);
+    dbprepare("get_geoms", prepare);
 }
 
 void gen_tile_raster_union_t::process(tile_t const &tile)
diff --git a/src/gen/gen-tile-vector.cpp b/src/gen/gen-tile-vector.cpp
index 2686691a8..ea2262a96 100644
--- a/src/gen/gen-tile-vector.cpp
+++ b/src/gen/gen-tile-vector.cpp
@@ -36,48 +36,48 @@ gen_tile_vector_union_t::gen_tile_vector_union_t(pg_conn_t *connection,
     }
 
     if (with_group_by()) {
-        dbexec(R"(
-PREPARE gen_geoms (int, int, int) AS
- WITH gen_tile_input AS (
-  SELECT "{group_by_column}" AS col, "{geom_column}" AS geom FROM {src}
-   WHERE "{geom_column}" && ST_TileEnvelope($1, $2, $3, margin => {margin})
- ),
- buffered AS (
-  SELECT col, ST_Buffer(geom, {buffer_size}) AS geom
-   FROM gen_tile_input
- ),
- merged AS (
-  SELECT col, ST_Union(geom) AS geom
-   FROM buffered GROUP BY col
- ),
- unbuffered AS (
-  SELECT col, ST_Buffer(ST_Buffer(geom, -2 * {buffer_size}), {buffer_size}) AS geom
-   FROM merged
- )
- INSERT INTO {dest} (x, y, "{group_by_column}", "{geom_column}")
-  SELECT $2, $3, col, (ST_Dump(geom)).geom FROM unbuffered
+        dbprepare("gen_geoms", R"(
+WITH gen_tile_input AS (
+ SELECT "{group_by_column}" AS col, "{geom_column}" AS geom FROM {src}
+  WHERE "{geom_column}" &&
+        ST_TileEnvelope($1::int, $2::int, $3::int, margin => {margin})
+),
+buffered AS (
+ SELECT col, ST_Buffer(geom, {buffer_size}) AS geom
+  FROM gen_tile_input
+),
+merged AS (
+ SELECT col, ST_Union(geom) AS geom
+  FROM buffered GROUP BY col
+),
+unbuffered AS (
+ SELECT col, ST_Buffer(ST_Buffer(geom, -2 * {buffer_size}), {buffer_size}) AS geom
+  FROM merged
+)
+INSERT INTO {dest} (x, y, "{group_by_column}", "{geom_column}")
+ SELECT $2::int, $3::int, col, (ST_Dump(geom)).geom FROM unbuffered
 )");
     } else {
-        dbexec(R"(
-PREPARE gen_geoms (int, int, int) AS
- WITH gen_tile_input AS (
-  SELECT "{geom_column}" AS geom FROM {src}
-   WHERE "{geom_column}" && ST_TileEnvelope($1, $2, $3, margin => {margin})
- ),
- buffered AS (
-  SELECT ST_Buffer(geom, {buffer_size}) AS geom
-   FROM gen_tile_input
- ),
- merged AS (
-  SELECT ST_Union(geom) AS geom
-   FROM buffered
- ),
- unbuffered AS (
-  SELECT ST_Buffer(ST_Buffer(geom, -2 * {buffer_size}), {buffer_size}) AS geom
-   FROM merged
- )
- INSERT INTO {dest} (x, y, "{geom_column}")
-  SELECT $2, $3, (ST_Dump(geom)).geom FROM unbuffered
+        dbprepare("gen_geoms", R"(
+WITH gen_tile_input AS (
+ SELECT "{geom_column}" AS geom FROM {src}
+  WHERE "{geom_column}" &&
+        ST_TileEnvelope($1::int, $2::int, $3::int, margin => {margin})
+),
+buffered AS (
+ SELECT ST_Buffer(geom, {buffer_size}) AS geom
+  FROM gen_tile_input
+),
+merged AS (
+ SELECT ST_Union(geom) AS geom
+  FROM buffered
+),
+unbuffered AS (
+ SELECT ST_Buffer(ST_Buffer(geom, -2 * {buffer_size}), {buffer_size}) AS geom
+  FROM merged
+)
+INSERT INTO {dest} (x, y, "{geom_column}")
+ SELECT $2::int, $3::int, (ST_Dump(geom)).geom FROM unbuffered
 )");
     }
 }
diff --git a/src/gen/gen-tile.cpp b/src/gen/gen-tile.cpp
index eb9dc22bc..3941e08af 100644
--- a/src/gen/gen-tile.cpp
+++ b/src/gen/gen-tile.cpp
@@ -23,8 +23,8 @@ gen_tile_t::gen_tile_t(pg_conn_t *connection, bool append, params_t *params)
     m_with_group_by = !get_params().get_identifier("group_by_column").empty();
 
     if (append_mode()) {
-        dbexec("PREPARE del_geoms (int, int) AS"
-               " DELETE FROM {dest} WHERE x=$1 AND y=$2");
+        dbprepare("del_geoms",
+                  "DELETE FROM {dest} WHERE x=$1::int AND y=$2::int");
     }
 }