diff --git a/cores/esp8266/heap.cpp b/cores/esp8266/heap.cpp
index 2001579ef..3f549716f 100644
--- a/cores/esp8266/heap.cpp
+++ b/cores/esp8266/heap.cpp
@@ -164,7 +164,7 @@ void ICACHE_RAM_ATTR print_loc(size_t size, const char* file, int line)
         if (inISR && (uint32_t)file >= 0x40200000) {
             DEBUG_HEAP_PRINTF("File: %p", file);
         } else if (!inISR && (uint32_t)file >= 0x40200000) {
-            char buf[ets_strlen(file)] __attribute__ ((aligned(4)));
+            char buf[ets_strlen(file) + 1] __attribute__((aligned(4)));
             ets_strcpy(buf, file);
             DEBUG_HEAP_PRINTF(buf);
         } else {
diff --git a/cores/esp8266/umm_malloc/umm_local.c b/cores/esp8266/umm_malloc/umm_local.c
index 8f83f4b4a..392ef13c8 100644
--- a/cores/esp8266/umm_malloc/umm_local.c
+++ b/cores/esp8266/umm_malloc/umm_local.c
@@ -206,7 +206,7 @@ int ICACHE_FLASH_ATTR umm_info_safe_printf_P(const char *fmt, ...) {
       the PROGMEM address must be word (4 bytes) aligned. The destination
       address for ets_memcpy must also be word-aligned.
     */
-    char ram_buf[ets_strlen(fmt)] __attribute__ ((aligned(4)));
+    char ram_buf[ets_strlen(fmt) + 1] __attribute__((aligned(4)));
     ets_strcpy(ram_buf, fmt);
     va_list argPtr;
     va_start(argPtr, fmt);