diff --git a/mlir/lib/Parser/Parser.cpp b/mlir/lib/Parser/Parser.cpp
--- a/mlir/lib/Parser/Parser.cpp
+++ b/mlir/lib/Parser/Parser.cpp
@@ -1958,11 +1958,8 @@
     return emitError(nameLoc, "redefinition of block '") << name << "'";
 
   // If an argument list is present, parse it.
-  if (consumeIf(Token::l_paren)) {
-    if (parseOptionalBlockArgList(block) ||
-        parseToken(Token::r_paren, "expected ')' to end argument list"))
-      return failure();
-  }
+  if (parseOptionalBlockArgList(block))
+    return failure();
 
   if (parseToken(Token::colon, "expected ':' after block name"))
     return failure();
@@ -2038,9 +2035,10 @@
   bool definingExistingArgs = owner->getNumArguments() != 0;
   unsigned nextArgument = 0;
 
-  return parseCommaSeparatedList([&]() -> ParseResult {
-    return parseSSADefOrUseAndType(
-        [&](SSAUseInfo useInfo, Type type) -> ParseResult {
+  return parseCommaSeparatedList(
+      Delimiter::OptionalParen, [&]() -> ParseResult {
+        return parseSSADefOrUseAndType([&](SSAUseInfo useInfo,
+                                           Type type) -> ParseResult {
           BlockArgument arg;
 
           // If we are defining existing arguments, ensure that the argument
@@ -2071,7 +2069,7 @@
 
           return addDefinition(useInfo, arg);
         });
-  });
+      });
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/IR/invalid.mlir b/mlir/test/IR/invalid.mlir
--- a/mlir/test/IR/invalid.mlir
+++ b/mlir/test/IR/invalid.mlir
@@ -136,7 +136,7 @@
 // -----
 
 func @block_no_rparen() {
-^bb42 (%bb42 : i32: // expected-error {{expected ')' to end argument list}}
+^bb42 (%bb42 : i32: // expected-error {{expected ')'}}
   return
 }
 
diff --git a/mlir/test/IR/parser.mlir b/mlir/test/IR/parser.mlir
--- a/mlir/test/IR/parser.mlir
+++ b/mlir/test/IR/parser.mlir
@@ -181,6 +181,12 @@
 // CHECK: }
 }
 
+// CHECK-LABEL: func @block_label_empty_list
+func @block_label_empty_list() {
+^bb0():
+  return
+}
+
 // CHECK-LABEL: func @multiblock() {
 func @multiblock() {
   return     // CHECK:   return