diff --git a/core/definitions.mk b/core/definitions.mk
index 1ab6388..ade8a9c 100644
--- a/core/definitions.mk
+++ b/core/definitions.mk
@@ -3286,7 +3286,7 @@
 	$(hide) mkdir -p "$$(dir $$@)"
 	$(hide) rm -f "$$@"
 	$(hide) \
-	    if $(LLVM_READOBJ) -h "$$<" >/dev/null 2>&1; then \
+	    if $(LLVM_READOBJ) -h "$$<" 2>/dev/null | grep -q "^Format: elf"; then \
 	        $(call echo-error,$(2),$(3)); \
 	        $(call echo-error,$(2),found ELF file: $$<); \
 	        false; \