diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 04c99f36ff7f..627a03ebb987 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -27,9 +27,13 @@ struct pt_regs {
 #define thumb_mode(regs) (0)
 #endif
 
+#ifndef CONFIG_CPU_V7M
 #define isa_mode(regs) \
-	((((regs)->ARM_cpsr & PSR_J_BIT) >> 23) | \
-	 (((regs)->ARM_cpsr & PSR_T_BIT) >> 5))
+	((((regs)->ARM_cpsr & PSR_J_BIT) >> (__ffs(PSR_J_BIT) - 1)) | \
+	 (((regs)->ARM_cpsr & PSR_T_BIT) >> (__ffs(PSR_T_BIT))))
+#else
+#define isa_mode(regs) 1 /* Thumb */
+#endif
 
 #define processor_mode(regs) \
 	((regs)->ARM_cpsr & MODE_MASK)