diff --git a/mlir/lib/Dialect/Affine/Analysis/AffineStructures.cpp b/mlir/lib/Dialect/Affine/Analysis/AffineStructures.cpp
--- a/mlir/lib/Dialect/Affine/Analysis/AffineStructures.cpp
+++ b/mlir/lib/Dialect/Affine/Analysis/AffineStructures.cpp
@@ -38,10 +38,10 @@
 void FlatAffineValueConstraints::addInductionVarOrTerminalSymbol(Value val) {
   if (containsVar(val))
     return;
-
+  
   // Caller is expected to fully compose map/operands if necessary.
-  assert((isTopLevelValue(val) || isAffineInductionVar(val)) &&
-         "non-terminal symbol / loop IV expected");
+  assert((isValidSymbol(val) || isAffineInductionVar(val)) &&
+         "valid symbol / loop IV expected");
   // Outer loop IVs could be used in forOp's bounds.
   if (auto loop = getForInductionVarOwner(val)) {
     appendDimVar(val);
@@ -58,7 +58,7 @@
     return;
   }
 
-  // Add top level symbol.
+  // Add valid symbol.
   appendSymbolVar(val);
   // Check if the symbol is a constant.
   if (std::optional<int64_t> constOp = getConstantIntValue(val))
diff --git a/mlir/lib/Dialect/Affine/IR/AffineOps.cpp b/mlir/lib/Dialect/Affine/IR/AffineOps.cpp
--- a/mlir/lib/Dialect/Affine/IR/AffineOps.cpp
+++ b/mlir/lib/Dialect/Affine/IR/AffineOps.cpp
@@ -378,7 +378,7 @@
   return false;
 }
 
-/// A value can be used as a symbol for `region` iff it meets one of the
+/// A value can be used as a symbol for `region` if it meets one of the
 /// following conditions:
 /// *) It is a constant.
 /// *) It is the result of an affine apply operation with symbol arguments.
diff --git a/mlir/test/Dialect/Affine/parallelize.mlir b/mlir/test/Dialect/Affine/parallelize.mlir
--- a/mlir/test/Dialect/Affine/parallelize.mlir
+++ b/mlir/test/Dialect/Affine/parallelize.mlir
@@ -323,3 +323,32 @@
   }
   return
 }
+
+// CHECK-LABEL: @no_toplevel_block_parallelize
+func.func @no_toplevel_block_parallelize(%arg0: i1) {
+  %c0 = arith.constant 0 : index
+  %c1 = arith.constant 1 : index
+  %c2 = arith.constant 2 : index
+  %alloc_0 = memref.alloc() : memref<2x3x6xi1>
+
+  scf.if %arg0 {
+    %alloc_1 = memref.alloc() : memref<2x3x6x9xi1>
+    %dim_0 = memref.dim %alloc_0, %c0 : memref<2x3x6xi1>
+    %dim_1 = memref.dim %alloc_0, %c1 : memref<2x3x6xi1>
+    affine.for %arg2 = 0 to %dim_0 {
+      affine.for %arg3 = 0 to %dim_1 {
+        affine.for %arg4 = 0 to 6 {
+          affine.for %arg5 = 0 to 9 {
+            %load_0 = affine.load %alloc_0[%arg2, %arg3, %arg4] : memref<2x3x6xi1>
+            affine.store %load_0, %alloc_1[%arg2, %arg3, %arg4, %arg5] : memref<2x3x6x9xi1>
+          }
+        }
+      }
+    }
+  }
+  // CHECK: affine.parallel (%{{.*}}) = (0) to (symbol(%{{.*}})) {
+  // CHECK:   affine.parallel (%{{.*}}) = (0) to (symbol(%{{.*}})) {
+  // CHECK:    affine.parallel (%{{.*}}) = (0) to (6) {
+  // CHECK:      affine.parallel (%{{.*}}) = (0) to (9) {
+  return
+}