diff --git a/libc/include/string.h b/libc/include/string.h
index b34d6504..dc58e4d8 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -48,10 +48,10 @@ extern "C"
     char* strerror(int errnum);
 
     /* Return the length of the initial segment of str which consists only of bytes in accept. */
-    usize strspn(const char* str, const char* accept);
+    size_t strspn(const char* str, const char* accept);
 
     /* Return the length of the initial segment of str which consists only of bytes not in reject. */
-    usize strcspn(const char* str, const char* reject);
+    size_t strcspn(const char* str, const char* reject);
 
     /* Separate a string into several tokens. */
     char* strtok(char* str, const char* delim);