diff --git a/dmd/identifier.c b/dmd/identifier.c
index 9960b856..9f3a7e4c 100644
--- a/dmd/identifier.c
+++ b/dmd/identifier.c
@@ -93,7 +93,7 @@ Identifier *Identifier::generateId(const char *prefix, size_t i)
 {   OutBuffer buf;
 
     buf.writestring(prefix);
-    buf.printf("%zu", i);
+    buf.printf("%"PRIuSIZE, i);
 
     char *id = buf.toChars();
     buf.data = NULL;
diff --git a/dmd2/identifier.c b/dmd2/identifier.c
index 1ac1d15a..6dab4129 100644
--- a/dmd2/identifier.c
+++ b/dmd2/identifier.c
@@ -93,7 +93,7 @@ Identifier *Identifier::generateId(const char *prefix, size_t i)
 {   OutBuffer buf;
 
     buf.writestring(prefix);
-    buf.printf("%zu", i);
+    buf.printf("%"PRIuSIZE, i);
 
     char *id = buf.toChars();
     buf.data = NULL;