diff --git a/src/target/cortex_m.c b/src/target/cortex_m.c
index fba832c78..ce3ab09c0 100644
--- a/src/target/cortex_m.c
+++ b/src/target/cortex_m.c
@@ -392,7 +392,9 @@ static int cortex_m_examine_debug_reason(struct target *target)
 			target->debug_reason = DBG_REASON_WATCHPOINT;
 		else if (cortex_m->nvic_dfsr & DFSR_VCATCH)
 			target->debug_reason = DBG_REASON_BREAKPOINT;
-		else	/* EXTERNAL, HALTED */
+		else if (cortex_m->nvic_dfsr & DFSR_EXTERNAL)
+			target->debug_reason = DBG_REASON_DBGRQ;
+		else	/* HALTED */
 			target->debug_reason = DBG_REASON_UNDEFINED;
 	}
 
diff --git a/src/target/cortex_m.h b/src/target/cortex_m.h
index c33486273..2f29903c8 100644
--- a/src/target/cortex_m.h
+++ b/src/target/cortex_m.h
@@ -127,6 +127,7 @@
 #define DFSR_BKPT			2
 #define DFSR_DWTTRAP		4
 #define DFSR_VCATCH			8
+#define DFSR_EXTERNAL		16
 
 #define FPCR_CODE 0
 #define FPCR_LITERAL 1