diff --git a/arch/arm/src/arm/arm_undefinedinsn.c b/arch/arm/src/arm/arm_undefinedinsn.c
index 807d41d1d65..bbb35525ef5 100644
--- a/arch/arm/src/arm/arm_undefinedinsn.c
+++ b/arch/arm/src/arm/arm_undefinedinsn.c
@@ -57,7 +57,7 @@
 
 void arm_undefinedinsn(uint32_t *regs)
 {
-  _alert("Undefined instruction at 0x%x\n", regs[REG_PC]);
+  _alert("Undefined instruction at 0x%" PRIx32 "\n", regs[REG_PC]);
   CURRENT_REGS = regs;
   PANIC();
 }