diff --git a/reactos/lib/sdk/crt/crt.rbuild b/reactos/lib/sdk/crt/crt.rbuild
index 99d3e2a4137..035908ea74e 100644
--- a/reactos/lib/sdk/crt/crt.rbuild
+++ b/reactos/lib/sdk/crt/crt.rbuild
@@ -316,6 +316,7 @@
 		<file>amsg.c</file>
 		<file>assert.c</file>
 		<file>environ.c</file>
+		<file>fltused.c</file>
 		<file>getargs.c</file>
 		<file>i10output.c</file>
 		<file>initterm.c</file>
diff --git a/reactos/lib/sdk/crt/libcntpr.rbuild b/reactos/lib/sdk/crt/libcntpr.rbuild
index ca472b54487..cb52f8868d4 100644
--- a/reactos/lib/sdk/crt/libcntpr.rbuild
+++ b/reactos/lib/sdk/crt/libcntpr.rbuild
@@ -127,6 +127,10 @@
 		<file>memicmp.c</file>
 	</directory>
 
+	<directory name="misc">
+		<file>fltused.c</file>
+	</directory>
+
 	<directory name="search">
 		<file>bsearch.c</file>
 		<file>lfind.c</file>