diff --git a/feedgen/ext/geo_entry.py b/feedgen/ext/geo_entry.py
index 03e8f41..2fcc409 100644
--- a/feedgen/ext/geo_entry.py
+++ b/feedgen/ext/geo_entry.py
@@ -294,7 +294,7 @@ class GeoEntryExtension(BaseEntryExtension):
 
         if geojson['type'] == 'Point':
 
-            coords = '%f %f'.format(
+            coords = '{:f} {:f}'.format(
                 geojson['coordinates'][1],  # latitude is y
                 geojson['coordinates'][0]
             )
@@ -303,7 +303,7 @@ class GeoEntryExtension(BaseEntryExtension):
         elif geojson['type'] == 'LineString':
 
             coords = ' '.join(
-                '%f %f'.format(vertex[1], vertex[0])
+                '{:f} {:f}'.format(vertex[1], vertex[0])
                 for vertex in
                 geojson['coordinates']
             )
@@ -315,7 +315,7 @@ class GeoEntryExtension(BaseEntryExtension):
                 warnings.warn(GeoRSSPolygonInteriorWarning(geom))
 
             coords = ' '.join(
-                '%f %f'.format(vertex[1], vertex[0])
+                '{:f} {:f}'.format(vertex[1], vertex[0])
                 for vertex in
                 geojson['coordinates'][0]
             )
diff --git a/tests/test_extensions/test_geo.py b/tests/test_extensions/test_geo.py
index 3855bf4..35dfa84 100644
--- a/tests/test_extensions/test_geo.py
+++ b/tests/test_extensions/test_geo.py
@@ -26,7 +26,7 @@ class Geom(object):
     def __str__(self):
         if self.geom_type == 'Point':
 
-            coords = '%f %f'.format(
+            coords = '{:f} {:f}'.format(
                 self.coords[1],  # latitude is y
                 self.coords[0]
             )
@@ -35,7 +35,7 @@ class Geom(object):
         elif self.geom_type == 'LineString':
 
             coords = ' '.join(
-                '%f %f'.format(vertex[1], vertex[0])
+                '{:f} {:f}'.format(vertex[1], vertex[0])
                 for vertex in
                 self.coords
             )
@@ -44,7 +44,7 @@ class Geom(object):
         elif self.geom_type == 'Polygon':
 
             coords = ' '.join(
-                '%f %f'.format(vertex[1], vertex[0])
+                '{:f} {:f}'.format(vertex[1], vertex[0])
                 for vertex in
                 self.coords[0]
             )
@@ -54,7 +54,7 @@ class Geom(object):
             # box not really supported by GeoJSON, but it's a handy cheat here
             # for testing
             coords = ' '.join(
-                '%f %f'.format(vertex[1], vertex[0])
+                '{:f} {:f}'.format(vertex[1], vertex[0])
                 for vertex in
                 self.coords
             )