diff --git a/ports/arm/platforms/qemu_integratorcp/modules.c b/ports/arm/platforms/qemu_integratorcp/modules.c
index 96312a1..86c658a 100644
--- a/ports/arm/platforms/qemu_integratorcp/modules.c
+++ b/ports/arm/platforms/qemu_integratorcp/modules.c
@@ -33,6 +33,7 @@
 #include "atomport-private.h"
 #include "atom.h"
 #include "atomport.h"
+#include "uart.h"
  
 
 /** Imports required by C startup code */
@@ -170,3 +171,15 @@ __interrupt_dispatcher (void)
 
 }
 
+
+/**
+ * \b null_handler
+ *
+ * Handler to catch interrupts at uninitialised vectors.
+ *
+ */
+void null_handler (void) 
+{
+	uart_write_halt ("Unhandled interrupt\n");
+}
+
diff --git a/ports/arm/platforms/qemu_integratorcp/startup.s b/ports/arm/platforms/qemu_integratorcp/startup.s
index a19ea76..1537d74 100644
--- a/ports/arm/platforms/qemu_integratorcp/startup.s
+++ b/ports/arm/platforms/qemu_integratorcp/startup.s
@@ -20,13 +20,13 @@
 __interrupt_vector_table:
 
   B Reset_Handler /* Reset */
-  B . /* Undefined */
-  B . /* SWI */
-  B . /* Prefetch Abort */
-  B . /* Data Abort */
-  B . /* reserved */
-  B IRQ_Handler /* IRQ */
-  B . /* FIQ */
+  B Null_Handler  /* Undefined */
+  B Null_Handler  /* SWI */
+  B Null_Handler  /* Prefetch Abort */
+  B Null_Handler  /* Data Abort */
+  B Null_Handler  /* reserved */
+  B IRQ_Handler   /* IRQ */
+  B Null_Handler  /* FIQ */
 
  
 
@@ -49,3 +49,5 @@ Reset_Handler:
 IRQ_Handler:
 	B archIRQHandler
 	
+Null_Handler:
+	B null_handler
diff --git a/ports/arm/platforms/qemu_integratorcp/uart.c b/ports/arm/platforms/qemu_integratorcp/uart.c
index a57a194..36ab27a 100644
--- a/ports/arm/platforms/qemu_integratorcp/uart.c
+++ b/ports/arm/platforms/qemu_integratorcp/uart.c
@@ -218,3 +218,38 @@ int uart_write (const char *ptr, int len)
     return len;
 }
 
+
+/**
+ * \b uart_write_halt
+ *
+ * Simple polled UART write for handling critical failures
+ * by printing out a message on the UART and looping forever.
+ * Can be called from interrupt (unlike the standard
+ * uart_write()) but is not thread-safe because it cannot
+ * take the thread-safety mutex, and hence is only useful for
+ * a last-resort catastrophic debug message.
+ *
+ * @param[in] ptr Pointer to write string
+ */
+void uart_write_halt (const char *ptr)
+{
+    /* Check parameters */
+    if (ptr != NULL)
+    {
+        /* Loop through all bytes until NULL terminator encountered */
+        while (*ptr != '\0')
+        {
+            /* Wait for empty */
+            while(UART_FR(UART0_ADDR) & UART_FR_TXFF)
+                ;
+
+            /* Write byte to UART */
+            UART_DR(UART0_ADDR) = *ptr++;
+        }
+    }
+
+    /* Loop forever */
+    while (1)
+        ;
+
+}
diff --git a/ports/arm/platforms/qemu_integratorcp/uart.h b/ports/arm/platforms/qemu_integratorcp/uart.h
index 57018c4..20fac85 100644
--- a/ports/arm/platforms/qemu_integratorcp/uart.h
+++ b/ports/arm/platforms/qemu_integratorcp/uart.h
@@ -33,5 +33,6 @@
 /* UART driver APIs */
 extern int uart_read (char *ptr, int len);
 extern int uart_write (const char *ptr, int len);
+extern void uart_write_halt (const char *ptr);
 
 #endif /* __ATOM_UART_H */