diff --git a/AUTHORS b/AUTHORS
index 756b373457..97cfc021b0 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -147,6 +147,7 @@ Taketoshi Aono <brn@b6n.ch>
 Teddy Katz <teddy.katz@gmail.com>
 Tiancheng "Timothy" Gu <timothygu99@gmail.com>
 Tobias Burnus <burnus@net-b.de>
+Tobias Nießen <tniessen@tnie.de>
 Victor Costan <costan@gmail.com>
 Vlad Burlik <vladbph@gmail.com>
 Vladimir Krivosheev <develar@gmail.com>
diff --git a/src/arm/simulator-arm.cc b/src/arm/simulator-arm.cc
index e8eb474090..10ff0d0f85 100644
--- a/src/arm/simulator-arm.cc
+++ b/src/arm/simulator-arm.cc
@@ -514,7 +514,7 @@ void ArmDebugger::Debug() {
         PrintF("    Stops are debug instructions inserted by\n");
         PrintF("    the Assembler::stop() function.\n");
         PrintF("    When hitting a stop, the Simulator will\n");
-        PrintF("    stop and and give control to the ArmDebugger.\n");
+        PrintF("    stop and give control to the ArmDebugger.\n");
         PrintF("    The first %d stop codes are watched:\n",
                Simulator::kNumOfWatchedStops);
         PrintF("    - They can be enabled / disabled: the Simulator\n");
diff --git a/src/mips/simulator-mips.cc b/src/mips/simulator-mips.cc
index 2bace20c7d..9ad68307ef 100644
--- a/src/mips/simulator-mips.cc
+++ b/src/mips/simulator-mips.cc
@@ -751,7 +751,7 @@ void MipsDebugger::Debug() {
         PrintF("    Stops are debug instructions inserted by\n");
         PrintF("    the Assembler::stop() function.\n");
         PrintF("    When hitting a stop, the Simulator will\n");
-        PrintF("    stop and and give control to the Debugger.\n");
+        PrintF("    stop and give control to the Debugger.\n");
         PrintF("    All stop codes are watched:\n");
         PrintF("    - They can be enabled / disabled: the Simulator\n");
         PrintF("       will / won't stop when hitting them.\n");
diff --git a/src/mips64/simulator-mips64.cc b/src/mips64/simulator-mips64.cc
index 6e4a2ebd2a..f852177400 100644
--- a/src/mips64/simulator-mips64.cc
+++ b/src/mips64/simulator-mips64.cc
@@ -683,7 +683,7 @@ void MipsDebugger::Debug() {
         PrintF("    Stops are debug instructions inserted by\n");
         PrintF("    the Assembler::stop() function.\n");
         PrintF("    When hitting a stop, the Simulator will\n");
-        PrintF("    stop and and give control to the Debugger.\n");
+        PrintF("    stop and give control to the Debugger.\n");
         PrintF("    All stop codes are watched:\n");
         PrintF("    - They can be enabled / disabled: the Simulator\n");
         PrintF("       will / won't stop when hitting them.\n");
diff --git a/src/ppc/simulator-ppc.cc b/src/ppc/simulator-ppc.cc
index 6fd503c470..eeb93e2470 100644
--- a/src/ppc/simulator-ppc.cc
+++ b/src/ppc/simulator-ppc.cc
@@ -604,7 +604,7 @@ void PPCDebugger::Debug() {
         PrintF("    Stops are debug instructions inserted by\n");
         PrintF("    the Assembler::stop() function.\n");
         PrintF("    When hitting a stop, the Simulator will\n");
-        PrintF("    stop and and give control to the PPCDebugger.\n");
+        PrintF("    stop and give control to the PPCDebugger.\n");
         PrintF("    The first %d stop codes are watched:\n",
                Simulator::kNumOfWatchedStops);
         PrintF("    - They can be enabled / disabled: the Simulator\n");
diff --git a/src/s390/simulator-s390.cc b/src/s390/simulator-s390.cc
index 9d35992e83..d2475e7900 100644
--- a/src/s390/simulator-s390.cc
+++ b/src/s390/simulator-s390.cc
@@ -605,7 +605,7 @@ void S390Debugger::Debug() {
         PrintF("    Stops are debug instructions inserted by\n");
         PrintF("    the Assembler::stop() function.\n");
         PrintF("    When hitting a stop, the Simulator will\n");
-        PrintF("    stop and and give control to the S390Debugger.\n");
+        PrintF("    stop and give control to the S390Debugger.\n");
         PrintF("    The first %d stop codes are watched:\n",
                Simulator::kNumOfWatchedStops);
         PrintF("    - They can be enabled / disabled: the Simulator\n");