diff --git a/core/src/main/java/org/teavm/backend/wasm/intrinsics/LongIntrinsic.java b/core/src/main/java/org/teavm/backend/wasm/intrinsics/LongIntrinsic.java
index 43ad044aa..f1f9c662f 100644
--- a/core/src/main/java/org/teavm/backend/wasm/intrinsics/LongIntrinsic.java
+++ b/core/src/main/java/org/teavm/backend/wasm/intrinsics/LongIntrinsic.java
@@ -17,7 +17,9 @@ package org.teavm.backend.wasm.intrinsics;
 
 import org.teavm.ast.InvocationExpr;
 import org.teavm.backend.wasm.WasmRuntime;
+import org.teavm.backend.wasm.model.WasmNumType;
 import org.teavm.backend.wasm.model.expression.WasmCall;
+import org.teavm.backend.wasm.model.expression.WasmConversion;
 import org.teavm.backend.wasm.model.expression.WasmExpression;
 import org.teavm.backend.wasm.model.expression.WasmIntBinary;
 import org.teavm.backend.wasm.model.expression.WasmIntBinaryOperation;
@@ -65,16 +67,20 @@ public class LongIntrinsic implements WasmIntrinsic {
                         manager.generate(invocation.getArguments().get(0)),
                         manager.generate(invocation.getArguments().get(1)));
             case "numberOfLeadingZeros":
-                return new WasmIntUnary(WasmIntType.INT64, WasmIntUnaryOperation.CLZ,
-                        manager.generate(invocation.getArguments().get(0)));
+                return castToInt(new WasmIntUnary(WasmIntType.INT64, WasmIntUnaryOperation.CLZ,
+                        manager.generate(invocation.getArguments().get(0))));
             case "numberOfTrailingZeros":
-                return new WasmIntUnary(WasmIntType.INT64, WasmIntUnaryOperation.CTZ,
-                        manager.generate(invocation.getArguments().get(0)));
+                return castToInt(new WasmIntUnary(WasmIntType.INT64, WasmIntUnaryOperation.CTZ,
+                        manager.generate(invocation.getArguments().get(0))));
             case "bitCount":
-                return new WasmIntUnary(WasmIntType.INT64, WasmIntUnaryOperation.POPCNT,
-                        manager.generate(invocation.getArguments().get(0)));
+                return castToInt(new WasmIntUnary(WasmIntType.INT64, WasmIntUnaryOperation.POPCNT,
+                        manager.generate(invocation.getArguments().get(0))));
             default:
                 throw new AssertionError();
         }
     }
+
+    private WasmExpression castToInt(WasmExpression expr) {
+        return new WasmConversion(WasmNumType.INT64, WasmNumType.INT32, false, expr);
+    }
 }
diff --git a/core/src/main/java/org/teavm/backend/wasm/intrinsics/gc/IntNumIntrinsic.java b/core/src/main/java/org/teavm/backend/wasm/intrinsics/gc/IntNumIntrinsic.java
index db95b6189..4dbed27aa 100644
--- a/core/src/main/java/org/teavm/backend/wasm/intrinsics/gc/IntNumIntrinsic.java
+++ b/core/src/main/java/org/teavm/backend/wasm/intrinsics/gc/IntNumIntrinsic.java
@@ -17,7 +17,9 @@ package org.teavm.backend.wasm.intrinsics.gc;
 
 import org.teavm.ast.InvocationExpr;
 import org.teavm.backend.wasm.WasmRuntime;
+import org.teavm.backend.wasm.model.WasmNumType;
 import org.teavm.backend.wasm.model.expression.WasmCall;
+import org.teavm.backend.wasm.model.expression.WasmConversion;
 import org.teavm.backend.wasm.model.expression.WasmExpression;
 import org.teavm.backend.wasm.model.expression.WasmIntBinary;
 import org.teavm.backend.wasm.model.expression.WasmIntBinaryOperation;
@@ -51,16 +53,24 @@ public class IntNumIntrinsic implements WasmGCIntrinsic {
                         context.generate(invocation.getArguments().get(0)),
                         context.generate(invocation.getArguments().get(1)));
             case "numberOfLeadingZeros":
-                return new WasmIntUnary(wasmType, WasmIntUnaryOperation.CLZ,
-                        context.generate(invocation.getArguments().get(0)));
+                return castToInt(new WasmIntUnary(wasmType, WasmIntUnaryOperation.CLZ,
+                        context.generate(invocation.getArguments().get(0))));
             case "numberOfTrailingZeros":
-                return new WasmIntUnary(wasmType, WasmIntUnaryOperation.CTZ,
-                        context.generate(invocation.getArguments().get(0)));
+                return castToInt(new WasmIntUnary(wasmType, WasmIntUnaryOperation.CTZ,
+                        context.generate(invocation.getArguments().get(0))));
             case "bitCount":
-                return new WasmIntUnary(wasmType, WasmIntUnaryOperation.POPCNT,
-                        context.generate(invocation.getArguments().get(0)));
+                return castToInt(new WasmIntUnary(wasmType, WasmIntUnaryOperation.POPCNT,
+                        context.generate(invocation.getArguments().get(0))));
             default:
                 throw new AssertionError();
         }
     }
+
+    private WasmExpression castToInt(WasmExpression expr) {
+        if (wasmType == WasmIntType.INT64) {
+            return new WasmConversion(WasmNumType.INT64, WasmNumType.INT32, false, expr);
+        } else {
+            return expr;
+        }
+    }
 }