diff --git a/tcl/target/stm32l.cfg b/tcl/target/stm32l.cfg
index 5d6a53e0b..37bd50512 100644
--- a/tcl/target/stm32l.cfg
+++ b/tcl/target/stm32l.cfg
@@ -27,7 +27,7 @@ if { [info exists WORKAREASIZE] } {
 
 # JTAG speed should be <= F_CPU/6.
 # F_CPU after reset is 2MHz, so use F_JTAG max = 333kHz
-adapter_khz 100
+adapter_khz 300
 
 adapter_nsrst_delay 100
 if {[using_jtag]} {
@@ -89,3 +89,6 @@ $_TARGETNAME configure -event reset-init {
 	stm32l_enable_HSI
 }
 
+$_TARGETNAME configure -event reset-start {
+	adapter_khz 300
+}