diff --git a/src/binaryen-c.cpp b/src/binaryen-c.cpp
index c273a3af42e..21e65065094 100644
--- a/src/binaryen-c.cpp
+++ b/src/binaryen-c.cpp
@@ -5878,6 +5878,10 @@ BinaryenType BinaryenFunctionGetVar(BinaryenFunctionRef func,
   assert(index < vars.size());
   return vars[index].getID();
 }
+BinaryenIndex BinaryenFunctionAddVar(BinaryenFunctionRef func,
+                                     BinaryenType type) {
+  return Builder::addVar((Function*)func, (Type)type);
+}
 BinaryenIndex BinaryenFunctionGetNumLocals(BinaryenFunctionRef func) {
   return ((Function*)func)->getNumLocals();
 }
diff --git a/src/binaryen-c.h b/src/binaryen-c.h
index 82de2dae934..b12cdc21332 100644
--- a/src/binaryen-c.h
+++ b/src/binaryen-c.h
@@ -3197,6 +3197,10 @@ BINARYEN_API BinaryenIndex BinaryenFunctionGetNumVars(BinaryenFunctionRef func);
 // specified `Function`.
 BINARYEN_API BinaryenType BinaryenFunctionGetVar(BinaryenFunctionRef func,
                                                  BinaryenIndex index);
+// Appends a local variable to the specified `Function`, returning its
+// index.
+BINARYEN_API BinaryenIndex BinaryenFunctionAddVar(BinaryenFunctionRef func,
+                                                  BinaryenType type);
 // Gets the number of locals within the specified function. Includes parameters.
 BINARYEN_API BinaryenIndex
 BinaryenFunctionGetNumLocals(BinaryenFunctionRef func);
diff --git a/test/example/c-api-kitchen-sink.c b/test/example/c-api-kitchen-sink.c
index d3368a6b147..fec0f2577b4 100644
--- a/test/example/c-api-kitchen-sink.c
+++ b/test/example/c-api-kitchen-sink.c
@@ -1417,6 +1417,16 @@ void test_core() {
   BinaryenFunctionRef sinker = BinaryenAddFunction(
     module, "kitchen()sinker", iIfF, BinaryenTypeInt32(), localTypes, 2, body);
 
+  BinaryenIndex numLocals = BinaryenFunctionGetNumLocals(sinker);
+  BinaryenIndex numParams =
+    BinaryenTypeArity(BinaryenFunctionGetParams(sinker));
+  BinaryenIndex newLocalIdx =
+    BinaryenFunctionAddVar(sinker, BinaryenTypeFloat32());
+  assert(newLocalIdx == numLocals);
+  assert(BinaryenFunctionGetNumLocals(sinker) == numLocals + 1);
+  assert(BinaryenFunctionGetVar(sinker, newLocalIdx - numParams) ==
+         BinaryenTypeFloat32());
+
   // Globals
 
   BinaryenAddGlobal(
diff --git a/test/example/c-api-kitchen-sink.txt b/test/example/c-api-kitchen-sink.txt
index 75c71b4ab01..5342236e147 100644
--- a/test/example/c-api-kitchen-sink.txt
+++ b/test/example/c-api-kitchen-sink.txt
@@ -102,6 +102,7 @@ BinaryenFeatureAll: 131071
  (func $"kitchen()sinker" (type $2) (param $0 i32) (param $1 i64) (param $2 f32) (param $3 f64) (result i32)
   (local $4 i32)
   (local $5 externref)
+  (local $6 f32)
   (block $the-body (result i32)
    (block $the-nothing
     (drop