diff --git a/tcl/target/efm32.cfg b/tcl/target/efm32.cfg
index 33610d5a8..e0c553fd2 100644
--- a/tcl/target/efm32.cfg
+++ b/tcl/target/efm32.cfg
@@ -1,5 +1,8 @@
 #
-# efm32 target
+# Silicon Labs (formerly Energy Micro) EFM32 target
+#
+# Note: All EFM32 chips have SWD support, but only newer series 1
+# chips have JTAG support.
 #
 
 source [find target/swj-dp.tcl]
@@ -21,10 +24,14 @@ if { [info exists WORKAREASIZE] } {
 if { [info exists CPUTAPID] } {
    set _CPUTAPID $CPUTAPID
 } else {
-   set _CPUTAPID 0x2ba01477
+   if { [using_jtag] } {
+      set _CPUTAPID 0x4ba00477
+   } {
+      set _CPUTAPID 0x2ba01477
+   }
 }
 
-swj_newdap $_CHIPNAME cpu -expected-id $_CPUTAPID
+swj_newdap $_CHIPNAME cpu -irlen 4 -ircapture 0x1 -irmask 0xf -expected-id $_CPUTAPID
 
 adapter_khz 1000