diff --git a/src/cmd/gc/const.c b/src/cmd/gc/const.c
index e4c1a784ab..5720efc8e9 100644
--- a/src/cmd/gc/const.c
+++ b/src/cmd/gc/const.c
@@ -348,13 +348,9 @@ toint(Val v)
 	return v;
 }
 
-void
-overflow(Val v, Type *t)
+int
+doesoverflow(Val v, Type *t)
 {
-	// v has already been converted
-	// to appropriate form for t.
-	if(t == T || t->etype == TIDEAL)
-		return;
 	switch(v.ctype) {
 	case CTINT:
 	case CTRUNE:
@@ -362,14 +358,14 @@ overflow(Val v, Type *t)
 			fatal("overflow: %T integer constant", t);
 		if(mpcmpfixfix(v.u.xval, minintval[t->etype]) < 0 ||
 		   mpcmpfixfix(v.u.xval, maxintval[t->etype]) > 0)
-			yyerror("constant %B overflows %T", v.u.xval, t);
+			return 1;
 		break;
 	case CTFLT:
 		if(!isfloat[t->etype])
 			fatal("overflow: %T floating-point constant", t);
 		if(mpcmpfltflt(v.u.fval, minfltval[t->etype]) <= 0 ||
 		   mpcmpfltflt(v.u.fval, maxfltval[t->etype]) >= 0)
-			yyerror("constant %#F overflows %T", v.u.fval, t);
+			return 1;
 		break;
 	case CTCPLX:
 		if(!iscomplex[t->etype])
@@ -378,7 +374,33 @@ overflow(Val v, Type *t)
 		   mpcmpfltflt(&v.u.cval->real, maxfltval[t->etype]) >= 0 ||
 		   mpcmpfltflt(&v.u.cval->imag, minfltval[t->etype]) <= 0 ||
 		   mpcmpfltflt(&v.u.cval->imag, maxfltval[t->etype]) >= 0)
-			yyerror("constant %#F overflows %T", v.u.fval, t);
+			return 1;
+		break;
+	}
+	return 0;
+}
+
+void
+overflow(Val v, Type *t)
+{
+	// v has already been converted
+	// to appropriate form for t.
+	if(t == T || t->etype == TIDEAL)
+		return;
+
+	if(!doesoverflow(v, t))
+		return;
+
+	switch(v.ctype) {
+	case CTINT:
+	case CTRUNE:
+		yyerror("constant %B overflows %T", v.u.xval, t);
+		break;
+	case CTFLT:
+		yyerror("constant %#F overflows %T", v.u.fval, t);
+		break;
+	case CTCPLX:
+		yyerror("constant %#F overflows %T", v.u.fval, t);
 		break;
 	}
 }
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index eb2345d6da..2fa6d95bef 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -178,7 +178,7 @@ struct	Type
 	Strlit*	note;		// literal string annotation
 
 	// TARRAY
-	int32	bound;		// negative is dynamic array
+	vlong	bound;		// negative is dynamic array
 
 	int32	maplineno;	// first use of TFORW as map key
 	int32	embedlineno;	// first use of TFORW as embedded type
@@ -977,6 +977,7 @@ int	isconst(Node *n, int ct);
 Node*	nodcplxlit(Val r, Val i);
 Node*	nodlit(Val v);
 long	nonnegconst(Node *n);
+int	doesoverflow(Val v, Type *t);
 void	overflow(Val v, Type *t);
 int	smallintconst(Node *n);
 Val	toint(Val v);
diff --git a/src/cmd/gc/typecheck.c b/src/cmd/gc/typecheck.c
index ebc43e7598..9869d560cb 100644
--- a/src/cmd/gc/typecheck.c
+++ b/src/cmd/gc/typecheck.c
@@ -390,8 +390,10 @@ reswitch:
 			if(t->bound < 0) {
 				yyerror("array bound must be non-negative");
 				goto error;
-			} else
-				overflow(v, types[TINT]);
+			} else if(doesoverflow(v, types[TINT])) {
+				yyerror("array bound is too large"); 
+				goto error;
+			}
 		}
 		typecheck(&r, Etype);
 		if(r->type == T)
diff --git a/test/fixedbugs/bug255.go b/test/fixedbugs/bug255.go
index dbd41cc6ab..acf4f23910 100644
--- a/test/fixedbugs/bug255.go
+++ b/test/fixedbugs/bug255.go
@@ -12,4 +12,4 @@ var c [1.5]int	// ERROR "truncated"
 var d ["abc"]int	// ERROR "invalid array bound|not numeric"
 var e [nil]int	// ERROR "invalid array bound|not numeric"
 var f [e]int	// ERROR "invalid array bound|not constant"
-var g [1<<65]int	// ERROR "overflows"
+var g [1<<65]int	// ERROR "array bound is too large|overflows"