diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 0c78442a7ee..e9adc5e0ed0 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -2037,7 +2037,11 @@ Type WasmBinaryReader::getType(int initial) {
   // Single value types are negative; signature indices are non-negative
   if (initial >= 0) {
     // TODO: Handle block input types properly.
-    return getSignatureByTypeIndex(initial).results;
+    auto sig = getSignatureByTypeIndex(initial);
+    if (sig.params != Type::none) {
+      throwError("control flow inputs are not supported yet");
+    }
+    return sig.results;
   }
   Type type;
   if (getBasicType(initial, type)) {
@@ -2088,7 +2092,7 @@ HeapType WasmBinaryReader::getIndexedHeapType() {
 Type WasmBinaryReader::getConcreteType() {
   auto type = getType();
   if (!type.isConcrete()) {
-    throw ParseException("non-concrete type when one expected");
+    throwError("non-concrete type when one expected");
   }
   return type;
 }
diff --git a/test/lit/binary/bad-multivalue-block.test b/test/lit/binary/bad-multivalue-block.test
new file mode 100644
index 00000000000..8b100fe89ed
--- /dev/null
+++ b/test/lit/binary/bad-multivalue-block.test
@@ -0,0 +1,16 @@
+;; Test that we error properly on a block with a bad multivalue (inputs).
+
+;; File contents:
+;;
+;; (module
+;;   (func $test
+;;     i32.const 0
+;;     (block (param i32)
+;;       drop
+;;     )
+;;   )
+;; )
+
+;; RUN: not wasm-opt -all %s.wasm 2>&1 | filecheck %s
+
+;; CHECK: control flow inputs are not supported yet
diff --git a/test/lit/binary/bad-multivalue-block.test.wasm b/test/lit/binary/bad-multivalue-block.test.wasm
new file mode 100644
index 00000000000..e44b9033f20
Binary files /dev/null and b/test/lit/binary/bad-multivalue-block.test.wasm differ
diff --git a/test/lit/binary/bad-multivalue-if.test b/test/lit/binary/bad-multivalue-if.test
new file mode 100644
index 00000000000..8fe20601285
--- /dev/null
+++ b/test/lit/binary/bad-multivalue-if.test
@@ -0,0 +1,22 @@
+;; Test that we error properly on an if with a bad multivalue (inputs).
+
+;; File contents:
+;;
+;; (module
+;;   (func $test
+;;     i32.const 0
+;;     i32.const 1
+;;     (if (param i32)
+;;       (then
+;;         drop
+;;       )
+;;       (else
+;;         drop
+;;       )
+;;     )
+;;   )
+;; )
+
+;; RUN: not wasm-opt -all %s.wasm 2>&1 | filecheck %s
+
+;; CHECK: control flow inputs are not supported yet
diff --git a/test/lit/binary/bad-multivalue-if.test.wasm b/test/lit/binary/bad-multivalue-if.test.wasm
new file mode 100644
index 00000000000..baddfec4ed7
Binary files /dev/null and b/test/lit/binary/bad-multivalue-if.test.wasm differ