diff --git a/src/api/java/Optimize.java b/src/api/java/Optimize.java
index 0b0a5bdaf..bc2232888 100644
--- a/src/api/java/Optimize.java
+++ b/src/api/java/Optimize.java
@@ -302,7 +302,7 @@ public class Optimize extends Z3Object {
      * Parse an SMT-LIB2 file with optimization objectives and constraints.
      * The parsed constraints and objectives are added to the optimization context.
      */
-    public void fromFile(string file)
+    public void fromFile(String file)
     {
 	Native.optimizeFromFile(getContext().nCtx(), getNativeObject(), file);
     }
@@ -310,7 +310,7 @@ public class Optimize extends Z3Object {
     /**
      * Similar to FromFile. Instead it takes as argument a string.
      */
-    public void fromString(string s)
+    public void fromString(String s)
     {
 	Native.optimizeFromString(getContext().nCtx(), getNativeObject(), s);
     }