diff --git a/python/src/deltachat/_build.py b/python/src/deltachat/_build.py
index 65d00ce1..2a38fbac 100644
--- a/python/src/deltachat/_build.py
+++ b/python/src/deltachat/_build.py
@@ -1,23 +1,35 @@
-import subprocess
+import distutils.ccompiler
+import distutils.sysconfig
 import tempfile
 
 import cffi
 
 
-ffibuilder = cffi.FFI()
-ffibuilder.set_source(
-    'deltachat.capi',
-    """
-    #include <deltachat/mrmailbox.h>
-    """,
-    libraries=['deltachat'],
-)
-with tempfile.NamedTemporaryFile(mode='r') as fp:
-    proc = subprocess.run(['gcc', '-E', '-o', fp.name, '-DPY_CFFI=1',
-                           '../src/mrmailbox.h'])
-    proc.check_returncode()
-    ffibuilder.cdef(fp.read())
+def ffibuilder():
+    builder = cffi.FFI()
+    builder.set_source(
+        'deltachat.capi',
+        """
+            #include <deltachat/mrmailbox.h>
+        """,
+        libraries=['deltachat'],
+    )
+    builder.cdef("""
+        typedef int... time_t;
+    """)
+    cc = distutils.ccompiler.new_compiler(force=True)
+    distutils.sysconfig.customize_compiler(cc)
+    with tempfile.NamedTemporaryFile(mode='w', suffix='.h') as src_fp:
+        src_fp.write('#include <deltachat/mrmailbox.h>')
+        src_fp.flush()
+        with tempfile.NamedTemporaryFile(mode='r') as dst_fp:
+            cc.preprocess(source=src_fp.name,
+                          output_file=dst_fp.name,
+                          macros=[('PY_CFFI', '1')])
+            builder.cdef(dst_fp.read())
+    return builder
 
 
 if __name__ == '__main__':
-    ffibuilder.compile(verbose=True)
+    builder = ffibuilder()
+    builder.compile(verbose=True)
diff --git a/src/mrmailbox.h b/src/mrmailbox.h
index 70d8c87f..c42ac497 100644
--- a/src/mrmailbox.h
+++ b/src/mrmailbox.h
@@ -150,18 +150,15 @@ extern "C" {
 #ifndef PY_CFFI
 #include <pthread.h>
 #include <libetpan/libetpan.h> /* defines uint16_t */
+#endif
+
 #include "mrarray.h"
-#endif
 #include "mrchatlist.h"
-#ifndef PY_CFFI
 #include "mrchat.h"
-#endif
 #include "mrmsg.h"
 #include "mrcontact.h"
-#ifndef PY_CFFI
 #include "mrlot.h"
 #include "mrevent.h"
-#endif
 
 
 /**
diff --git a/src/mrmsg.h b/src/mrmsg.h
index 58e2eb25..d2c6dde9 100644
--- a/src/mrmsg.h
+++ b/src/mrmsg.h
@@ -26,10 +26,6 @@
 extern "C" {
 #endif
 
-#ifdef PY_CFFI
-typedef int... time_t;
-#endif
-
 
 typedef struct _mrmailbox mrmailbox_t;