diff --git a/include/mapnik/sql_utils.hpp b/include/mapnik/sql_utils.hpp
index 52899997d..72d120a1b 100644
--- a/include/mapnik/sql_utils.hpp
+++ b/include/mapnik/sql_utils.hpp
@@ -37,6 +37,7 @@ MAPNIK_DISABLE_WARNING_POP
 #include <iosfwd>
 #include <regex>
 #include <string>
+#include <sstream>
 
 namespace mapnik { namespace sql_utils {
 
diff --git a/test/unit/datasource/spatial_index.cpp b/test/unit/datasource/spatial_index.cpp
index 65d62c17f..2ae435603 100644
--- a/test/unit/datasource/spatial_index.cpp
+++ b/test/unit/datasource/spatial_index.cpp
@@ -22,6 +22,8 @@
 
 #include "catch.hpp"
 
+#include <sstream>
+
 #include <mapnik/quad_tree.hpp>
 #include <mapnik/util/spatial_index.hpp>
 
diff --git a/test/unit/imaging/webp_io.cpp b/test/unit/imaging/webp_io.cpp
index 8f6d23be6..7e3d2e0fb 100644
--- a/test/unit/imaging/webp_io.cpp
+++ b/test/unit/imaging/webp_io.cpp
@@ -3,6 +3,8 @@
 
 #include "catch.hpp"
 
+#include <sstream>
+
 #include <mapnik/image_view.hpp>
 #include <mapnik/webp_io.hpp>