diff --git a/pkgs/development/compilers/gwt/builder.sh b/pkgs/development/compilers/gwt/builder.sh
index 4bf19a44f8b..d260bd559dc 100644
--- a/pkgs/development/compilers/gwt/builder.sh
+++ b/pkgs/development/compilers/gwt/builder.sh
@@ -16,7 +16,7 @@ cat > $out/bin/gwt-compile <<EOF
 export LD_LIBRARY_PATH=$libPath
 export LIBXCB_ALLOW_SLOPPY_LOCK=1 # Workaround for bug in Java AWT implementation
 
-$jdk/bin/java -Xmx128m -cp "\$CLASSPATH:$out/$name/gwt-user.jar:$out/$name/gwt-dev-linux.jar" com.google.gwt.dev.Compiler \$@
+$jdk/bin/java -Xmx256m -cp "\$CLASSPATH:$out/$name/gwt-user.jar:$out/$name/gwt-dev-linux.jar" com.google.gwt.dev.Compiler \$@
 EOF
 chmod 755 $out/bin/gwt-compile
 
@@ -26,6 +26,6 @@ cat > $out/bin/gwt-shell <<EOF
 export LD_LIBRARY_PATH=$libPath
 export LIBXCB_ALLOW_SLOPPY_LOCK=1 # Workaround for bug in Java AWT implementation
 
-$jdk/bin/java -Xmx128m -cp "\$CLASSPATH:$out/$name/gwt-user.jar:$out/$name/gwt-dev-linux.jar" com.google.gwt.dev.GWTShell \$@
+$jdk/bin/java -Xmx256m -cp "\$CLASSPATH:$out/$name/gwt-user.jar:$out/$name/gwt-dev-linux.jar" com.google.gwt.dev.GWTShell \$@
 EOF
 chmod 755 $out/bin/gwt-shell