diff --git a/Makefile b/Makefile
index ab107bc..7fa9752 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 all: test
 
 test: test.c uprintf.c uprintf.h
-	gcc -std=c99 -Os -o test test.c uprintf.c
+	gcc -std=c89 -Os -o test test.c uprintf.c
 
 clean:
 	rm -rf test
diff --git a/uprintf.c b/uprintf.c
index c1ac216..82da79a 100644
--- a/uprintf.c
+++ b/uprintf.c
@@ -66,12 +66,12 @@ static int l_strlen(const char *str)
 /* Helper functions for p() */
 static void print_string(put_char_func pc, const char *str, int width, char wchr)
 {
-    int sl;
+    int sl, w;
 
     if (width < 0)
     {
         sl = l_strlen(str);
-        for (int w = -width; w > sl; w --)
+        for (w = -width; w > sl; w --)
             pc(wchr);
     }
 
@@ -80,7 +80,7 @@ static void print_string(put_char_func pc, const char *str, int width, char wchr
 
     if (width > 0)
     {
-        for (int w = width; w > sl; w --)
+        for (w = width; w > sl; w --)
             pc(wchr);
     }
 }
diff --git a/uprintf.h b/uprintf.h
index 1104de5..5e0662e 100644
--- a/uprintf.h
+++ b/uprintf.h
@@ -12,4 +12,4 @@ void pp(put_char_func pc, const char *fmt, ...);
 void p(const char *fmt, ...);
 int psn(char *str, int size, const char *fmt, ...);
 
-#endif // _UPRINTF
+#endif /* _UPRINTF */