diff --git a/modules/preprocs/yapp/Makefile.inc b/modules/preprocs/yapp/Makefile.inc
index db445583..bfb6e090 100644
--- a/modules/preprocs/yapp/Makefile.inc
+++ b/modules/preprocs/yapp/Makefile.inc
@@ -11,3 +11,15 @@ BUILT_SOURCES += \
 
 CLEANFILES += \
 	yapp-token.c
+	src/tests/yapp_test.sh
+
+TESTS += \
+	src/preprocs/yapp/tests/yapp_test.sh
+
+EXTRA_DIST += \
+	src/preprocs/yapp/tests/define.asm \
+	src/preprocs/yapp/tests/define.pre
+
+CLEANFILES += \
+	define.yp
+
diff --git a/modules/preprocs/yapp/tests/define.asm b/modules/preprocs/yapp/tests/define.asm
new file mode 100644
index 00000000..f9330d39
--- /dev/null
+++ b/modules/preprocs/yapp/tests/define.asm
@@ -0,0 +1,4 @@
+%define foo 5
+%define bar baz
+	mov	ax, [foo+bar]
+%define baz bzzt
diff --git a/modules/preprocs/yapp/tests/define.pre b/modules/preprocs/yapp/tests/define.pre
new file mode 100644
index 00000000..5815282b
--- /dev/null
+++ b/modules/preprocs/yapp/tests/define.pre
@@ -0,0 +1,4 @@
+
+
+	mov	ax, [5+baz]
+
diff --git a/modules/preprocs/yapp/tests/yapp_test.sh b/modules/preprocs/yapp/tests/yapp_test.sh
new file mode 100755
index 00000000..e3137f9f
--- /dev/null
+++ b/modules/preprocs/yapp/tests/yapp_test.sh
@@ -0,0 +1,37 @@
+#!/bin/sh
+
+#
+# Verify that all test cases match
+# (aside from whitespace for now)
+#
+
+passedct=0
+passedlist=''
+failedct=0
+failedlist=''
+
+YT=" - YAPP_TEST"
+
+
+for asm in ${srcdir}/src/preprocs/yapp/tests/*.asm
+do
+    a=`echo ${asm} | sed -e 's,^.*/,,' | sed -e 's,.asm$,,'`
+    y=${a}.yp
+    p=`echo ${asm} | sed -e 's,.asm$,.pre,'`
+
+    echo "$YT: Testing yapp for ${a}"
+    ./yasm -e ${asm} > ${y}
+    if diff -w ${p} ${y} > /dev/null; then
+	passedct=`expr $passedct + 1`
+	passedlist="${passedlist}${a} "
+    else
+	failedct=`expr $failedct + 1`
+	failedlist="${failedlist}${a} "
+    fi
+    #rm ${y}
+done
+
+test $passedct -gt 0 && echo "$YT: PASSED $passedct: $passedlist"
+test $failedct -gt 0 && echo "$YT: FAILED $failedct: $failedlist"
+
+exit $failedct
diff --git a/src/preprocs/yapp/Makefile.inc b/src/preprocs/yapp/Makefile.inc
index db445583..bfb6e090 100644
--- a/src/preprocs/yapp/Makefile.inc
+++ b/src/preprocs/yapp/Makefile.inc
@@ -11,3 +11,15 @@ BUILT_SOURCES += \
 
 CLEANFILES += \
 	yapp-token.c
+	src/tests/yapp_test.sh
+
+TESTS += \
+	src/preprocs/yapp/tests/yapp_test.sh
+
+EXTRA_DIST += \
+	src/preprocs/yapp/tests/define.asm \
+	src/preprocs/yapp/tests/define.pre
+
+CLEANFILES += \
+	define.yp
+
diff --git a/src/preprocs/yapp/tests/define.asm b/src/preprocs/yapp/tests/define.asm
new file mode 100644
index 00000000..f9330d39
--- /dev/null
+++ b/src/preprocs/yapp/tests/define.asm
@@ -0,0 +1,4 @@
+%define foo 5
+%define bar baz
+	mov	ax, [foo+bar]
+%define baz bzzt
diff --git a/src/preprocs/yapp/tests/define.pre b/src/preprocs/yapp/tests/define.pre
new file mode 100644
index 00000000..5815282b
--- /dev/null
+++ b/src/preprocs/yapp/tests/define.pre
@@ -0,0 +1,4 @@
+
+
+	mov	ax, [5+baz]
+
diff --git a/src/preprocs/yapp/tests/yapp_test.sh b/src/preprocs/yapp/tests/yapp_test.sh
new file mode 100755
index 00000000..e3137f9f
--- /dev/null
+++ b/src/preprocs/yapp/tests/yapp_test.sh
@@ -0,0 +1,37 @@
+#!/bin/sh
+
+#
+# Verify that all test cases match
+# (aside from whitespace for now)
+#
+
+passedct=0
+passedlist=''
+failedct=0
+failedlist=''
+
+YT=" - YAPP_TEST"
+
+
+for asm in ${srcdir}/src/preprocs/yapp/tests/*.asm
+do
+    a=`echo ${asm} | sed -e 's,^.*/,,' | sed -e 's,.asm$,,'`
+    y=${a}.yp
+    p=`echo ${asm} | sed -e 's,.asm$,.pre,'`
+
+    echo "$YT: Testing yapp for ${a}"
+    ./yasm -e ${asm} > ${y}
+    if diff -w ${p} ${y} > /dev/null; then
+	passedct=`expr $passedct + 1`
+	passedlist="${passedlist}${a} "
+    else
+	failedct=`expr $failedct + 1`
+	failedlist="${failedlist}${a} "
+    fi
+    #rm ${y}
+done
+
+test $passedct -gt 0 && echo "$YT: PASSED $passedct: $passedlist"
+test $failedct -gt 0 && echo "$YT: FAILED $failedct: $failedlist"
+
+exit $failedct