diff --git a/doc/source/array.rst b/doc/source/array.rst
index 3d3ccbc78552602657a946dc8e301a664572988c..8df254c58275eadba9c07b298e063537dba05fcf 100644
--- a/doc/source/array.rst
+++ b/doc/source/array.rst
@@ -396,6 +396,13 @@ See the `source file
 <https://github.com/inducer/pyopencl/blob/master/src/cl/pyopencl-complex.h>`_
 for a precise list of what's available.
 
+If you need double precision support, please::
+
+    #define PYOPENCL_DEFINE_CDOUBLE
+
+before including the header, as DP support apparently cannot be reliably
+autodetected.
+
 Under the hood, the complex types are simply `float2` and `double2`.
 
 .. warning::
diff --git a/pyopencl/elementwise.py b/pyopencl/elementwise.py
index f9b115b192082dfc80e66d425401be4d83ca63c4..a4ec223e7a0f251230b49bee2511526af9a37ce1 100644
--- a/pyopencl/elementwise.py
+++ b/pyopencl/elementwise.py
@@ -85,7 +85,9 @@ def get_elwise_kernel_and_types(context, arguments, operation,
     for arg in parsed_args:
         if arg.dtype in [np.float64, np.complex128]:
             if not have_double_pragma:
-                pragmas.append("#pragma OPENCL EXTENSION cl_khr_fp64: enable\n")
+                pragmas.append(
+                        "#pragma OPENCL EXTENSION cl_khr_fp64: enable\n"
+                        "#define PYOPENCL_DEFINE_CDOUBLE\n")
                 have_double_pragma = True
         if arg.dtype.kind == 'c':
             if not have_complex_include:
diff --git a/src/cl/pyopencl-complex.h b/src/cl/pyopencl-complex.h
index 8e4093f2e3c99100c59a4cbe41334776ceaad2a6..2709ea422506d1100aeaa2f85e0c9010700ffaa1 100644
--- a/src/cl/pyopencl-complex.h
+++ b/src/cl/pyopencl-complex.h
@@ -219,7 +219,7 @@
 PYOPENCL_DECLARE_COMPLEX_TYPE(float, FLT);
 #define cfloat_cast(a) ((cfloat_t) ((a).x, (a).y))
 
-#ifdef DBL_EPSILON
+#ifdef PYOPENCL_DEFINE_CDOUBLE
 PYOPENCL_DECLARE_COMPLEX_TYPE(double, DBL);
 #define cdouble_cast(a) ((cdouble_t) ((a).x, (a).y))
 #endif