diff --git a/tools/bin2c/Makefile b/tools/bin2c/Makefile
index 303f322..2e64db4 100644
--- a/tools/bin2c/Makefile
+++ b/tools/bin2c/Makefile
@@ -1,5 +1,9 @@
 NATIVE_CC ?= gcc
 
+ifeq (, $(shell which $(NATIVE_CC) 2>/dev/null))
+$(error "Native GCC is missing. Please install it first. If it's path is custom, set it with export NATIVE_CC=<path to native gcc toolchain>")
+endif
+
 .PHONY: all clean
 
 all: bin2c
diff --git a/tools/lz/Makefile b/tools/lz/Makefile
index 8ffabde..6a70564 100644
--- a/tools/lz/Makefile
+++ b/tools/lz/Makefile
@@ -1,5 +1,9 @@
 NATIVE_CC ?= gcc
 
+ifeq (, $(shell which $(NATIVE_CC) 2>/dev/null))
+$(error "Native GCC is missing. Please install it first. If it's path is custom, set it with export NATIVE_CC=<path to native gcc toolchain>")
+endif
+
 .PHONY: all clean
 
 all: lz77
diff --git a/tools/lz/lz77.c b/tools/lz/lz77.c
index 812ae8d..9ab159d 100644
--- a/tools/lz/lz77.c
+++ b/tools/lz/lz77.c
@@ -33,7 +33,7 @@ int main(int argc, char *argv[])
 	if(stat(argv[1], &statbuf))
 		goto error;
 
-	if((in_file=fopen(argv[1], "r")) == NULL)
+	if((in_file=fopen(argv[1], "rb")) == NULL)
 		goto error;
 
 	strcpy(filename, argv[1]);