1 files changed, 8 insertions, 0 deletions
diff --git a/lib/libc/ctype/isupper.c b/lib/libc/ctype/isupper.c
new file mode 100644
index 00000000..458990df
--- /dev/null
+++ b/lib/libc/ctype/isupper.c
@@ -0,0 +1,8 @@
+#include <libc.h>
+
+int isupper(int c)
+{
+	return (unsigned)c - 'A' < 26;
+}
+
+weak_reference(isupper, isupper_l);