diff --git a/core/src/main/java/org/teavm/backend/wasm/render/WasmCRenderingVisitor.java b/core/src/main/java/org/teavm/backend/wasm/render/WasmCRenderingVisitor.java
index 11bbf00aa..19381165a 100644
--- a/core/src/main/java/org/teavm/backend/wasm/render/WasmCRenderingVisitor.java
+++ b/core/src/main/java/org/teavm/backend/wasm/render/WasmCRenderingVisitor.java
@@ -1064,20 +1064,24 @@ class WasmCRenderingVisitor implements WasmExpressionVisitor {
     public void visit(WasmFill expression) {
         var result = new CExpression();
 
+        requiredType = WasmType.INT32;
         expression.getIndex().acceptVisitor(this);
         var dest = value;
 
+        requiredType = WasmType.INT32;
         expression.getValue().acceptVisitor(this);
         var v = value;
 
-        expression.getValue().acceptVisitor(this);
+        requiredType = WasmType.INT32;
+        expression.getCount().acceptVisitor(this);
         var num = value;
 
         result.getLines().addAll(dest.getLines());
         result.getLines().addAll(v.getLines());
         result.getLines().addAll(num.getLines());
 
-        result.addLine("memset(" + dest.getText() + ", " + v.getText() + ", " + num.getText() + ");");
+        result.addLine("memset(wasm_heap + " + dest.getText() + ", " + v.getText()
+                + ", " + num.getText() + ");");
         value = result;
     }
 
@@ -1085,12 +1089,15 @@ class WasmCRenderingVisitor implements WasmExpressionVisitor {
     public void visit(WasmCopy expression) {
         var result = new CExpression();
 
+        requiredType = WasmType.INT32;
         expression.getDestinationIndex().acceptVisitor(this);
         var dest = value;
 
+        requiredType = WasmType.INT32;
         expression.getSourceIndex().acceptVisitor(this);
         var src = value;
 
+        requiredType = WasmType.INT32;
         expression.getCount().acceptVisitor(this);
         var num = value;
 
@@ -1098,7 +1105,8 @@ class WasmCRenderingVisitor implements WasmExpressionVisitor {
         result.getLines().addAll(src.getLines());
         result.getLines().addAll(num.getLines());
 
-        result.addLine("memcpy(" + dest.getText() + ", " + src.getText() + ", " + num.getText() + ");");
+        result.addLine("memcpy(wasm_heap + " + dest.getText() + ", wasm_heap + " + src.getText() + ", "
+                + num.getText() + ");");
         value = result;
     }
 
diff --git a/core/src/main/resources/org/teavm/backend/wasm/wasm-runtime.c b/core/src/main/resources/org/teavm/backend/wasm/wasm-runtime.c
index 5abdb5b22..3f6063157 100644
--- a/core/src/main/resources/org/teavm/backend/wasm/wasm-runtime.c
+++ b/core/src/main/resources/org/teavm/backend/wasm/wasm-runtime.c
@@ -21,7 +21,11 @@ static char** wasm_argv;
 #define teavmMath_ceil ceil
 #define teavmMath_floor floor
 
-int64_t teavm_currentTimeMillis() {
+double teavmMath_random() {
+    return rand() / (double) RAND_MAX;
+}
+
+double teavm_currentTimeMillis() {
     struct timespec time;
     clock_gettime(CLOCK_REALTIME, &time);
 
@@ -148,4 +152,11 @@ int32_t wasi_snapshot_preview1_fd_write(int32_t fd, int32_t iovs, int32_t count,
     int32_t* resultPtr = (int32_t*) (wasm_heap + result);
     *resultPtr = written;
     return 0;
+}
+
+void teavm_putwcharsOut(int32_t chars, int32_t count) {
+    int16_t* chars_array = (int16_t*) (wasm_heap + chars);
+    for (int32_t i = 0; i < count; ++i) {
+        putwchar(chars_array[i]);
+    }
 }
\ No newline at end of file