diff --git a/arch/arm/src/stm32l4/stm32l4_rcc.h b/arch/arm/src/stm32l4/stm32l4_rcc.h
index 405a919ff11..ff539b0d316 100644
--- a/arch/arm/src/stm32l4/stm32l4_rcc.h
+++ b/arch/arm/src/stm32l4/stm32l4_rcc.h
@@ -53,7 +53,7 @@
 #define EXTERN extern "C"
 extern "C"
 {
-#elseO
+#else
 #define EXTERN extern
 #endif