diff --git a/Sources/CWasm3/m3_parse.c b/Sources/CWasm3/m3_parse.c
index e1bdb7b..d313940 100644
--- a/Sources/CWasm3/m3_parse.c
+++ b/Sources/CWasm3/m3_parse.c
@@ -228,7 +228,7 @@ _       (ReadLEB_u32 (& index, & i_bytes, i_end));
         if (exportKind == d_externalKind_function)
         {
             u16 numNames = io_module->functions [index].numNames;
-            if (numNames < d_m3MaxDuplicateFunctionImpl - 1)
+            if (numNames < d_m3MaxDuplicateFunctionImpl)
             {
                 io_module->functions [index].numNames++;
                 io_module->functions [index].names[numNames] = utf8;
diff --git a/Tests/CWasm3Tests/CWasm3Tests.swift b/Tests/CWasm3Tests/CWasm3Tests.swift
index d202620..f8981b0 100644
--- a/Tests/CWasm3Tests/CWasm3Tests.swift
+++ b/Tests/CWasm3Tests/CWasm3Tests.swift
@@ -32,7 +32,14 @@ final class CWasm3Tests: XCTestCase {
         var constant2Function: IM3Function?
         XCTAssertNil(m3_FindFunction(&constant2Function, runtime, "constant_2"))
 
-        [constant1Function, constant2Function]
+        var constant3Function: IM3Function?
+        XCTAssertNil(m3_FindFunction(&constant3Function, runtime, "constant_3"))
+
+        var constant4Function: IM3Function?
+        let err = try XCTUnwrap(m3_FindFunction(&constant4Function, runtime, "constant_4"))
+        XCTAssertEqual("function lookup failed", String(cString: err))
+
+        [constant1Function, constant2Function, constant3Function]
             .forEach { (function) in
                 guard function != nil else { return XCTFail() }
                 let size = UnsafeMutablePointer<Int>.allocate(capacity: 1)
@@ -292,7 +299,7 @@ extension CWasm3Tests {
 
     private func constantWasm() throws -> Array<UInt8> {
         let base64 =
-            "AGFzbQEAAAABBQFgAAF/AwIBAAcbAgpjb25zdGFudF8xAAAKY29uc3RhbnRfMgAACggBBgBBgIAECw=="
+            "AGFzbQEAAAABBQFgAAF/AwIBAAc1BApjb25zdGFudF8xAAAKY29uc3RhbnRfMgAACmNvbnN0YW50XzMAAApjb25zdGFudF80AAAKCAEGAEGAgAQL"
         guard let data = Data(base64Encoded: base64)
         else { throw TestError.couldNotDecodeWasm("constant.wasm") }
         return Array<UInt8>(data)
diff --git a/Tests/CWasm3Tests/Resources/constant.wat b/Tests/CWasm3Tests/Resources/constant.wat
index b381f56..957b1b9 100644
--- a/Tests/CWasm3Tests/Resources/constant.wat
+++ b/Tests/CWasm3Tests/Resources/constant.wat
@@ -3,4 +3,6 @@
   (func (;0;) (type 0) (result i32)
     i32.const 65536)
   (export "constant_1" (func 0))
-  (export "constant_2" (func 0)))
+  (export "constant_2" (func 0))
+  (export "constant_3" (func 0))
+  (export "constant_4" (func 0)))