diff --git a/ports/run/gdb_monitor.run b/ports/run/gdb_monitor.run
index d48b5b03ff..1f11e0c1c3 100644
--- a/ports/run/gdb_monitor.run
+++ b/ports/run/gdb_monitor.run
@@ -129,6 +129,16 @@ append gdb_cmds {-ex "c" }
 # test: stack trace when not in syscall
 append gdb_cmds {-ex "bt" }
 
+# test: modify variable
+append gdb_cmds {-ex "print test_var" }
+append gdb_cmds {-ex "set var test_var=2" }
+append gdb_cmds {-ex "print test_var" }
+
+# test: 'call' command
+if {![have_spec nova]} {
+append gdb_cmds {-ex "call test_var_func()" }
+}
+
 # test: thread info
 append gdb_cmds {-ex "b Test_thread::entry()" }
 append gdb_cmds {-ex "c" }
@@ -150,7 +160,7 @@ append gdb_cmds {-ex "q" }
 # run GDB and redirect stderr to stdio to get the relevant output into the expect buffer  
 eval spawn [gdb] bin/$gdb_target_binary -batch $gdb_cmds 2&>1
 
-set timeout 60
+set timeout 120
 expect {
 	timeout { puts stderr "Error: Test execution timed out"; exit -2 }
 }
@@ -180,6 +190,23 @@ if {![regexp {#0  puts} $gdb_output] ||
 	exit -1
 }
 
+if {![regexp {\$1 = 1} $gdb_output]} {
+	puts stderr "Error: first 'print test_var' command didn't result in the expected output"
+	exit -1
+}
+
+if {![regexp {\$2 = 2} $gdb_output]} {
+	puts stderr "Error: second 'print test_var' command didn't result in the expected output"
+	exit -1
+}
+
+if {![have_spec nova]} {
+if {![regexp {\$3 = 3} $gdb_output]} {
+	puts stderr "Error: 'call' command didn't result in the expected output"
+	exit -1
+}
+}
+
 if {![regexp {Breakpoint 4, Test_thread::entry()} $gdb_output]} {
 	puts stderr "Error: Breakpoint in test thread did not trigger"
 	exit -1
@@ -191,7 +218,7 @@ if {![regexp {\* 2    Thread 2          Test_thread::entry} $gdb_output] ||
 	exit -1
 }
 
-if {![regexp {42				func()} $gdb_output]} {
+if {![regexp {46				func()} $gdb_output]} {
 	puts stderr "Error: Single stepping didn't result in the expected output"
 	exit -1
 }
diff --git a/ports/src/test/gdb_monitor/main.cc b/ports/src/test/gdb_monitor/main.cc
index 63a928f5f5..fde4594ab6 100644
--- a/ports/src/test/gdb_monitor/main.cc
+++ b/ports/src/test/gdb_monitor/main.cc
@@ -1,5 +1,5 @@
 /*
- * \brief  GDB Monitor thread selection and backtrace test
+ * \brief  GDB Monitor test
  * \author Christian Prochaska
  * \date   2011-05-24
  */
@@ -19,6 +19,10 @@
 /* libc includes */
 #include <stdio.h>
 
+/* a variable to be modified with GDB */
+int test_var = 1;
+
+/* a thread to test GDB thread switching support */
 class Test_thread : public Genode::Thread<2*4096>
 {
 	public:
@@ -45,6 +49,15 @@ class Test_thread : public Genode::Thread<2*4096>
 		}
 };
 
+/*
+ * This function returns the current value of 'test_var' + 1 and can be called from
+ * GDB using the 'call' or 'print' commands
+ */
+int test_var_func()
+{
+	return test_var + 1;
+}
+
 /* this function returns a value to make itself appear in the stack trace when building with -O2 */
 int func2()
 {
@@ -52,6 +65,9 @@ int func2()
 	 * thread which is not in a syscall */
 	puts("in func2()\n");
 
+	/* call 'test_var_func()', so the compiler does not throw the function away */
+	printf("test_var_func() returned %d\n", test_var_func());
+
 	return 0;
 }
 
@@ -77,3 +93,4 @@ int main(void)
 
 	return 0;
 }
+