diff --git a/assemble.c b/assemble.c
index b20c866..71c7d00 100644
--- a/assemble.c
+++ b/assemble.c
@@ -926,6 +926,10 @@ static int assemble(
                     return 1;
 
                 case P_EVEN:
+                    cp = skipwhite(cp);
+                    if (!EOL(*cp)) {
+                        report(stack->top, ".EVEN must not have an argument\n");
+                    }
                     if (DOT & 1) {
                         list_word(stack->top, DOT, 0, 1, "");
                         DOT++;
@@ -934,6 +938,9 @@ static int assemble(
                     return 1;
 
                 case P_ODD:
+                    if (!EOL(*cp)) {
+                        report(stack->top, ".EVEN must not have an argument\n");
+                    }
                     if (!(DOT & 1)) {
                         list_word(stack->top, DOT, 0, 1, "");
                         DOT++;
@@ -1121,9 +1128,19 @@ static int assemble(
                 case P_BLKW:
                 case P_BLKB:
                     {
-                        EX_TREE        *value = parse_expr(cp, 0);
+                        EX_TREE        *value;
                         int             ok = 1;
 
+                        cp = skipwhite(cp);
+                        if (EOL(*cp)) {
+                            /* If no argument, assume 1. Documented but
+                             * discouraged. Par 6.5.3, page 6-32. */
+                            /* warning(stack->top, "Argument to .BLKB/.BLKW should be present; 1 assumed\n"); */
+                            value = new_ex_lit(1);
+                        } else {
+                            value = parse_expr(cp, 0);
+                        }
+
                         if (value->type != EX_LIT) {
                             report(stack->top, "Argument to .BLKB/.BLKW " "must be constant\n");
                             ok = 0;
diff --git a/tests/RunTests b/tests/RunTests
index b9796be..76e506e 100755
--- a/tests/RunTests
+++ b/tests/RunTests
@@ -8,6 +8,7 @@
 
 TESTS="test-asciz \
     test-backpatch \
+    test-blkb \
     test-bsl-mac-arg \
     test-complex-reloc \
     test-endm \
diff --git a/tests/test-blkb.lst.ok b/tests/test-blkb.lst.ok
new file mode 100644
index 0000000..0ccced9
--- /dev/null
+++ b/tests/test-blkb.lst.ok
@@ -0,0 +1,41 @@
+       1                                ;;;;;
+       2                                ;
+       3                                ; Test .BLKB and .BLKW
+       4                                ;
+       5        000000                  label:	.blkb		; not recommended, but default argument is 1
+       6        000001                  	.blkb	1
+       7        000002                  	.blkb	2
+       8        000004                  	.blkb	100.
+test-blkb.mac:9: ***ERROR Argument to .BLKB/.BLKW must be constant
+       9                                	.blkb	label	; error: not an constant expression
+      10                                
+      11 000150    000                  	.odd
+      12                                
+      13        000151                  	.blkw	1	; should maybe be an error: odd address
+      14                                
+      15 000153    000                  	.even
+      16                                
+      17        000154                  label2:	.blkb		; not recommended, but default argument is 1
+      18        000155                  	.blkb	1
+      19        000156                  	.blkb	2
+      20        000160                  	.blkb	100.
+test-blkb.mac:21: ***ERROR Argument to .BLKB/.BLKW must be constant
+      21                                	.blkb	label2	; error: not an constant expression
+      22                                
+      23                                
+test-blkb.mac:24: ***ERROR .EVEN must not have an argument
+      24                                	.even	1	; error: no argument allowed
+test-blkb.mac:25: ***ERROR .EVEN must not have an argument
+      25 000324    000                  	.odd	1	; error: no argument allowed
+      25                                
+
+
+Symbol table
+
+.      ******R      001 LABEL  000000R      001 LABEL2 000154R      001 
+
+
+Program sections:
+
+. ABS.  000000    000   (RW,I,GBL,ABS,OVR,NOSAV)
+        000325    001   (RW,I,LCL,REL,CON,NOSAV)
diff --git a/tests/test-blkb.mac b/tests/test-blkb.mac
new file mode 100644
index 0000000..88e39eb
--- /dev/null
+++ b/tests/test-blkb.mac
@@ -0,0 +1,25 @@
+;;;;;
+;
+; Test .BLKB and .BLKW
+;
+label:	.blkb		; not recommended, but default argument is 1
+	.blkb	1
+	.blkb	2
+	.blkb	100.
+	.blkb	label	; error: not an constant expression
+
+	.odd
+
+	.blkw	1	; should maybe be an error: odd address
+
+	.even
+
+label2:	.blkb		; not recommended, but default argument is 1
+	.blkb	1
+	.blkb	2
+	.blkb	100.
+	.blkb	label2	; error: not an constant expression
+
+
+	.even	1	; error: no argument allowed
+	.odd	1	; error: no argument allowed