diff --git a/OvmfPkg/Include/Library/QemuFwCfgLib.h b/OvmfPkg/Include/Library/QemuFwCfgLib.h
index 8d3b835d43..baaa257d61 100644
--- a/OvmfPkg/Include/Library/QemuFwCfgLib.h
+++ b/OvmfPkg/Include/Library/QemuFwCfgLib.h
@@ -17,6 +17,12 @@
 #ifndef __FW_CFG_LIB__
 #define __FW_CFG_LIB__
 
+//
+// The size, in bytes, of names of firmware configuration files, including at
+// least one terminating NUL byte.
+//
+#define QEMU_FW_CFG_FNAME_SIZE 56
+
 typedef enum {
   QemuFwCfgItemSignature            = 0x0000,
   QemuFwCfgItemInterfaceVersion     = 0x0001,
diff --git a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
index 92c85c1d3d..24424f83a9 100644
--- a/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
+++ b/OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLib.c
@@ -278,7 +278,7 @@ QemuFwCfgFindFile (
     UINT32 FileSize;
     UINT16 FileSelect;
     UINT16 FileReserved;
-    CHAR8  FName[56];
+    CHAR8  FName[QEMU_FW_CFG_FNAME_SIZE];
 
     FileSize     = QemuFwCfgRead32 ();
     FileSelect   = QemuFwCfgRead16 ();