diff --git a/configure.ac b/configure.ac
index b4c66fb8..558489ce 100644
--- a/configure.ac
+++ b/configure.ac
@@ -561,7 +561,7 @@ case "${host}" in
 	dnl syscall(2) and secure_getenv(3) are exposed by _GNU_SOURCE.
 	JE_APPEND_VS(CPPFLAGS, -D_GNU_SOURCE)
 	abi="elf"
-	AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS])
+	AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS], [ ])
 	AC_DEFINE([JEMALLOC_HAS_ALLOCA_H])
 	AC_DEFINE([JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY], [ ])
 	AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
@@ -575,7 +575,7 @@ case "${host}" in
 	dnl syscall(2) and secure_getenv(3) are exposed by _GNU_SOURCE.
 	JE_APPEND_VS(CPPFLAGS, -D_GNU_SOURCE)
 	abi="elf"
-	AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS])
+	AC_DEFINE([JEMALLOC_PURGE_MADVISE_DONTNEED_ZEROS], [ ])
 	AC_DEFINE([JEMALLOC_HAS_ALLOCA_H])
 	AC_DEFINE([JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY], [ ])
 	AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])