diff --git a/core/src/main/java/org/teavm/backend/wasm/generate/WasmGeneratorUtil.java b/core/src/main/java/org/teavm/backend/wasm/generate/WasmGeneratorUtil.java
index 240746e1e..481220b8e 100644
--- a/core/src/main/java/org/teavm/backend/wasm/generate/WasmGeneratorUtil.java
+++ b/core/src/main/java/org/teavm/backend/wasm/generate/WasmGeneratorUtil.java
@@ -54,6 +54,8 @@ public final class WasmGeneratorUtil {
                 case DOUBLE:
                     return WasmType.FLOAT64;
             }
+        } else if (type == ValueType.VOID) {
+            return null;
         }
         return WasmType.INT32;
     }