diff --git a/include/internal.h b/include/internal.h
index c4a90a6c..470bbfb8 100644
--- a/include/internal.h
+++ b/include/internal.h
@@ -93,6 +93,15 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
 #ifdef HAVE_IA64INTRIN_H
 # define HAVE_CMPXCHG
 # include <ia64intrin.h>
+  /*
+   * ecc v7.0 is broken: it's missing __sync_val_compare_and_swap()
+   * even though the ia64 ABI requires it.  Work around it:
+   */
+# ifndef __sync_val_compare_and_swap
+#  define __sync_val_compare_and_swap(x,y,z)		\
+	_InterlockedCompareExchange64_rel(x,y,z)
+# endif
+
 # define cmpxchg_ptr(_ptr,_o,_n)					\
 	((void *) __sync_val_compare_and_swap((long *) (_ptr),		\
 					      (long) (_o), (long) (_n)))