diff --git a/tests/tcg/s390x/Makefile.target b/tests/tcg/s390x/Makefile.target
index dbf64c9..19fbbc6 100644
--- a/tests/tcg/s390x/Makefile.target
+++ b/tests/tcg/s390x/Makefile.target
@@ -38,6 +38,7 @@
 TESTS+=mxdb
 TESTS+=epsw
 TESTS+=larl
+TESTS+=mdeb
 
 cdsg: CFLAGS+=-pthread
 cdsg: LDFLAGS+=-pthread
diff --git a/tests/tcg/s390x/mdeb.c b/tests/tcg/s390x/mdeb.c
new file mode 100644
index 0000000..4897d28
--- /dev/null
+++ b/tests/tcg/s390x/mdeb.c
@@ -0,0 +1,30 @@
+/*
+ * Test the MDEB and MDEBR instructions.
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <assert.h>
+#include <stdlib.h>
+
+int main(void)
+{
+    union {
+        float f[2];
+        double d;
+    } a;
+    float b;
+
+    a.f[0] = 1.2345;
+    a.f[1] = 999;
+    b = 6.789;
+    asm("mdeb %[a],%[b]" : [a] "+f" (a.d) : [b] "R" (b));
+    assert(a.d > 8.38 && a.d < 8.39);
+
+    a.f[0] = 1.2345;
+    a.f[1] = 999;
+    b = 6.789;
+    asm("mdebr %[a],%[b]" : [a] "+f" (a.d) : [b] "f" (b));
+    assert(a.d > 8.38 && a.d < 8.39);
+
+    return EXIT_SUCCESS;
+}