diff -Naurp gcc/config/avr/avr-devices.c gcc/config/avr/avr-devices.c
--- gcc/config/avr/avr-devices.c	2011-05-13 17:35:31.000000000 -0500
+++ gcc/config/avr/avr-devices.c	2011-05-13 17:43:10.000000000 -0500
@@ -113,6 +113,7 @@ const struct mcu_type_s avr_mcu_types[] 
   { "atmega16u2",           ARCH_AVR35, "__AVR_ATmega16U2__",       0, 0x0100, "m16u2" },
   { "atmega32u2",           ARCH_AVR35, "__AVR_ATmega32U2__",       0, 0x0100, "m32u2" },
   { "attiny167",            ARCH_AVR35, "__AVR_ATtiny167__",        0, 0x0100, "tn167" },
+  { "attiny1634",           ARCH_AVR35, "__AVR_ATtiny1634__",       0, 0x0100, "tn1634" },
     /* Enhanced, <= 8K.  */
   { "avr4",                 ARCH_AVR4, NULL,                        0, 0x0060, "m8" },
   { "atmega8",              ARCH_AVR4, "__AVR_ATmega8__",           0, 0x0060, "m8" },
diff -Naurp gcc/config/avr/t-avr gcc/config/avr/t-avr
--- gcc/config/avr/t-avr	2011-05-13 17:35:31.000000000 -0500
+++ gcc/config/avr/t-avr	2011-05-13 17:37:41.000000000 -0500
@@ -152,6 +152,7 @@ MULTILIB_MATCHES = \
 	mmcu?avr35=mmcu?atmega16u2 \
 	mmcu?avr35=mmcu?atmega32u2 \
 	mmcu?avr35=mmcu?attiny167 \
+	mmcu?avr35=mmcu?attiny1634 \
 	mmcu?avr4=mmcu?atmega48 \
 	mmcu?avr4=mmcu?atmega48a \
 	mmcu?avr4=mmcu?atmega48p \