diff --git a/assemble.c b/assemble.c
index 01285ee..a1a90f2 100644
--- a/assemble.c
+++ b/assemble.c
@@ -1241,7 +1241,7 @@ static int assemble(
                                 return 0;
                             }
 
-                            if (op->value == 0100 && (mode.type & 07) == 0) {
+                            if (op->value == 0100 && (mode.type & 070) == 0) {
                                 report(stack->top, "JMP Rn is illegal\n");
                                 /* But encode it anyway... */
                             }
diff --git a/tests/RunTests b/tests/RunTests
index fbebf29..b80f350 100755
--- a/tests/RunTests
+++ b/tests/RunTests
@@ -6,7 +6,7 @@
 # If there is a .objd.ok file, it compares the result of dumpobj.
 #
 
-TESTS="test-asciz test-backpatch test-bsl-mac-arg test-complex-reloc test-endm test-include test-locals test-macro-comma test-undef test-word-comma"
+TESTS="test-asciz test-backpatch test-bsl-mac-arg test-complex-reloc test-endm test-include test-jmp test-locals test-macro-comma test-undef test-word-comma"
 
 for t in $TESTS
 do
diff --git a/tests/test-jmp.mac b/tests/test-jmp.mac
new file mode 100644
index 0000000..d9b0ca9
--- /dev/null
+++ b/tests/test-jmp.mac
@@ -0,0 +1,17 @@
+;;;;;
+;
+; Tests the addressing modes for JMP.
+; JMP Rx is not allowed, all other modes are.
+;
+
+start:  jmp     end
+        jmp     r1              ; must fail
+        jmp     (r1)
+        jmp     (r1)+
+        jmp     @(r1)+
+        jmp     -(r1)
+        jmp     @-(r1)
+        jmp     1234(r1)
+        jmp     @1234(r1)
+
+end: