diff --git a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
index d88185a..ae09cd1 100644
--- a/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/JavaMethodWasmCodeBuilder.java
@@ -16,7 +16,6 @@
 package de.inetsoftware.jwebassembly.module;
 
 import java.io.IOException;
-import java.util.List;
 
 import javax.annotation.Nonnull;
 
@@ -126,11 +125,11 @@ class JavaMethodWasmCodeBuilder extends WasmCodeBuilder {
                         addConstInstruction( Integer.valueOf( byteCode.readShort() ), ValueType.i32, codePos, lineNumber );
                         break;
                     case 18: // ldc
-                        addConstInstruction( (Number)constantPool.get( byteCode.readUnsignedByte() ), codePos, lineNumber );
+                        addConstInstruction( constantPool.get( byteCode.readUnsignedByte() ), codePos, lineNumber );
                         break;
                     case 19: // ldc_w
                     case 20: // ldc2_w
-                        addConstInstruction( (Number)constantPool.get( byteCode.readUnsignedShort() ), codePos, lineNumber );
+                        addConstInstruction( constantPool.get( byteCode.readUnsignedShort() ), codePos, lineNumber );
                         break;
                     case 21: // iload
                         addLoadStoreInstruction( ValueType.i32, true, byteCode.readUnsignedIndex( wide ), codePos, lineNumber );
diff --git a/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java b/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
index 073394c..946292d 100644
--- a/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
+++ b/src/de/inetsoftware/jwebassembly/module/WasmCodeBuilder.java
@@ -17,7 +17,9 @@ package de.inetsoftware.jwebassembly.module;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.function.Function;
 
 import javax.annotation.Nonnegative;
@@ -59,6 +61,8 @@ public abstract class WasmCodeBuilder {
 
     private WasmOptions                 options;
 
+    private Map<String, Integer>        strings        = new LinkedHashMap<>();
+
     /**
      * Initialize the code builder;
      * 
@@ -308,8 +312,17 @@ public abstract class WasmCodeBuilder {
      * @param lineNumber
      *            the line number in the Java source code
      */
-    protected void addConstInstruction( Number value, int javaCodePos, int lineNumber ) {
-        instructions.add( new WasmConstInstruction( value, javaCodePos, lineNumber ) );
+    protected void addConstInstruction( Object value, int javaCodePos, int lineNumber ) {
+        if( value.getClass() == String.class ) {
+            Integer id = strings.get( value );
+            if( id == null ) {
+                strings.put( (String)value, id = strings.size() );
+            }
+            FunctionName name = getNonGC( "stringConstant", lineNumber );
+            addCallInstruction( name, javaCodePos, lineNumber );
+        } else {
+            instructions.add( new WasmConstInstruction( (Number)value, javaCodePos, lineNumber ) );
+        }
     }
 
     /**