diff --git a/arch/arm/src/samv7/sam_systemreset.c b/arch/arm/src/samv7/sam_systemreset.c
index 60957b8e10a..fbc9f19daf2 100644
--- a/arch/arm/src/samv7/sam_systemreset.c
+++ b/arch/arm/src/samv7/sam_systemreset.c
@@ -77,7 +77,7 @@ void up_systemreset(void)
 
   rstmr  = getreg32(SAM_RSTC_MR);
   rstmr &= ~RSTC_MR_ERSTL_MASK;
-  rstmr &= RSTC_MR_ERSTL(CONFIG_SAMV7_EXTRESET_ERST) | RSTC_MR_KEY;
+  rstmr &= RSTC_MR_ERSTL(CONFIG_SAMV7_EXTRESET_ERST-1) | RSTC_MR_KEY;
   putreg32(rstmr, SAM_RSTC_MR);
 #endif