diff --git a/django/contrib/gis/gdal/prototypes/generation.py b/django/contrib/gis/gdal/prototypes/generation.py
index bba715d67c..1303532372 100644
--- a/django/contrib/gis/gdal/prototypes/generation.py
+++ b/django/contrib/gis/gdal/prototypes/generation.py
@@ -8,6 +8,9 @@ from django.contrib.gis.gdal.prototypes.errcheck import \
     check_arg_errcode, check_errcode, check_geom, check_geom_offset, \
     check_pointer, check_srs, check_str_arg, check_string, check_const_string
 
+class gdal_char_p(c_char_p):
+    pass
+
 def double_output(func, argtypes, errcheck=False, strarg=False):
     "Generates a ctypes function that returns a double value."
     func.argtypes = argtypes
@@ -77,9 +80,9 @@ def string_output(func, argtypes, offset=-1, str_result=False):
     """
     func.argtypes = argtypes
     if str_result:
-        # String is the result, don't explicitly define
-        # the argument type so we can get the pointer.
-        pass
+        # Use subclass of c_char_p so the error checking routine
+        # can free the memory at the pointer's address.
+        func.restype = gdal_char_p
     else:
         # Error code is returned
         func.restype = c_int
diff --git a/django/contrib/gis/geos/prototypes/topology.py b/django/contrib/gis/geos/prototypes/topology.py
index 633340901b..65c26f9f37 100644
--- a/django/contrib/gis/geos/prototypes/topology.py
+++ b/django/contrib/gis/geos/prototypes/topology.py
@@ -10,6 +10,7 @@ __all__ = ['geos_boundary', 'geos_buffer', 'geos_centroid', 'geos_convexhull',
 from ctypes import c_char_p, c_double, c_int
 from django.contrib.gis.geos.libgeos import lgeos, GEOM_PTR, GEOS_PREPARE
 from django.contrib.gis.geos.prototypes.errcheck import check_geom, check_string
+from django.contrib.gis.geos.prototypes.geom import geos_char_p
 
 def topology(func, *args):
     "For GEOS unary topology functions."
@@ -38,6 +39,7 @@ geos_union = topology(lgeos.GEOSUnion, GEOM_PTR)
 # GEOSRelate returns a string, not a geometry.
 geos_relate = lgeos.GEOSRelate
 geos_relate.argtypes = [GEOM_PTR, GEOM_PTR]
+geos_relate.restype = geos_char_p
 geos_relate.errcheck = check_string
 
 # Routines only in GEOS 3.1+