diff --git a/INSTALL b/INSTALL
index d7496612..042f8291 100644
--- a/INSTALL
+++ b/INSTALL
@@ -161,9 +161,11 @@ any of the following arguments (not a definitive list) to 'configure':
 --disable-munmap
     Disable virtual memory deallocation via munmap(2); instead keep track of
     the virtual memory for later use.  munmap() is disabled by default (i.e.
-    --disable-munmap is implied) on Linux, which has a quirk in its virtual
-    memory allocation algorithm that causes semi-permanent VM map holes under
-    normal jemalloc operation.
+    --disable-munmap is implied) on [64-bit] Linux, which has a quirk in its
+    virtual memory allocation algorithm that causes semi-permanent VM map holes
+    under normal jemalloc operation.  Although munmap() causes issues on 32-bit
+    Linux as well, it is not disabled by default due to the practical
+    possibility of address space exhaustion.
 
 --disable-fill
     Disable support for junk/zero filling of memory.  See the "opt.junk" and
diff --git a/configure.ac b/configure.ac
index a3cfc88f..f6d08ccd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -557,7 +557,9 @@ case "${host}" in
 	AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
 	AC_DEFINE([JEMALLOC_C11_ATOMICS])
 	force_tls="0"
-	default_munmap="0"
+	if "${LG_SIZEOF_PTR}" = "3"; then
+	  default_munmap="0"
+	fi
 	;;
   *-*-linux* | *-*-kfreebsd*)
 	dnl syscall(2) and secure_getenv(3) are exposed by _GNU_SOURCE.
@@ -568,7 +570,9 @@ case "${host}" in
 	AC_DEFINE([JEMALLOC_PROC_SYS_VM_OVERCOMMIT_MEMORY], [ ])
 	AC_DEFINE([JEMALLOC_THREADED_INIT], [ ])
 	AC_DEFINE([JEMALLOC_USE_CXX_THROW], [ ])
-	default_munmap="0"
+	if "${LG_SIZEOF_PTR}" = "3"; then
+	  default_munmap="0"
+	fi
 	;;
   *-*-netbsd*)
 	AC_MSG_CHECKING([ABI])