diff --git a/chapter08/zlib.xml b/chapter08/zlib.xml
index 1d1d2d4d1..74c075ee4 100644
--- a/chapter08/zlib.xml
+++ b/chapter08/zlib.xml
@@ -76,7 +76,7 @@
 
     <para>Prepare Zlib for compilation:</para>
 
-<screen><userinput remap="configure">CFLAGS+="-m32" CXXFLAGS+="-m32" \
+<screen><userinput remap="configure">CFLAGS+=" -m32" CXXFLAGS+=" -m32" \
 ./configure --prefix=/usr \
     --libdir=/usr/lib32</userinput></screen>
 
@@ -103,7 +103,7 @@ rm -rf DESTDIR</userinput></screen>
 
     <para>Prepare Zlib for compilation:</para>
 
-<screen><userinput remap="configure">CFLAGS+="-mx32" CXXFLAGS+="-mx32" \
+<screen><userinput remap="configure">CFLAGS+=" -mx32" CXXFLAGS+=" -mx32" \
 ./configure --prefix=/usr    \
     --libdir=/usr/libx32</userinput></screen>