--- Include/objimpl.h
+++ Include/objimpl.h
@@ -250,7 +250,7 @@
         union _gc_head *gc_prev;
         Py_ssize_t gc_refs;
     } gc;
-    double dummy;  /* force worst-case alignment */
+    long double dummy;  /* force worst-case alignment */
 } PyGC_Head;
 
 extern PyGC_Head *_PyGC_generation0;
--- Objects/obmalloc.c
+++ Objects/obmalloc.c
@@ -413,8 +413,8 @@
 
 #ifdef WITH_PYMALLOC
 
+#define WITH_VALGRIND
 #ifdef WITH_VALGRIND
-#include <valgrind/valgrind.h>
 
 /* If we're using GCC, use __builtin_expect() to reduce overhead of
    the valgrind checks */
@@ -1181,7 +1181,7 @@
 
 #ifdef WITH_VALGRIND
     if (UNLIKELY(running_on_valgrind == -1))
-        running_on_valgrind = RUNNING_ON_VALGRIND;
+        running_on_valgrind = 1;
     if (UNLIKELY(running_on_valgrind))
         goto redirect;
 #endif