diff --git a/src/prim.c b/src/prim.c
index 86e5cba..43f0374 100644
--- a/src/prim.c
+++ b/src/prim.c
@@ -336,11 +336,11 @@ struct Prim_Init {
      */
     { P_Quote,             "quote",                          1, 1,    NOEVAL },
     { P_Quasiquote,        "quasiquote",                     1, 1,    NOEVAL },
-    { P_Begin,             "begin",                          1, MANY, NOEVAL },
-    { P_Begin1,            "begin1",                         1, MANY, NOEVAL },
+    { P_Begin,             "begin",                          0, MANY, NOEVAL },
+    { P_Begin1,            "begin1",                         0, MANY, NOEVAL },
     { P_If,                "if",                             2, MANY, NOEVAL },
     { P_Case,              "case",                           2, MANY, NOEVAL },
-    { P_Cond,              "cond",                           1, MANY, NOEVAL },
+    { P_Cond,              "cond",                           0, MANY, NOEVAL },
     { P_Do,                "do",                             2, MANY, NOEVAL },
     { P_Let,               "let",                            2, MANY, NOEVAL },
     { P_Letseq,            "let*",                           2, MANY, NOEVAL },
diff --git a/src/special.c b/src/special.c
index df6387a..b90f192 100644
--- a/src/special.c
+++ b/src/special.c
@@ -131,7 +131,7 @@ Object P_Begin (Object forms) {
     TC_Prolog;
 
     if (Nullp (forms))
-        return Null;
+        return Unspecified;
     GC_Link (forms);
     TC_Disable;
     for ( ; !Nullp (Cdr (forms)); forms = Cdr (forms))
@@ -147,6 +147,8 @@ Object P_Begin1 (Object forms) {
     GC_Node;
     TC_Prolog;
 
+    if (Nullp (forms))
+        return Unspecified;
     GC_Link (forms);
     TC_Disable;
     for (n = 1; !Nullp (Cdr (forms)); n = 0, forms = Cdr (forms)) {
@@ -229,6 +231,9 @@ Object P_Cond (Object argl) {
     GC_Node3;
     TC_Prolog;
 
+    if (Nullp (argl))
+        return Unspecified;
+
     ret = False;
     clause = guard = Null;
     GC_Link3 (argl, clause, guard);