diff --git a/avogadro/io/dcdformat.cpp b/avogadro/io/dcdformat.cpp
index bdfc705457..8391ac042b 100644
--- a/avogadro/io/dcdformat.cpp
+++ b/avogadro/io/dcdformat.cpp
@@ -34,7 +34,7 @@ using Core::UnitCell;
 #ifndef _WIN32
 #endif
 
-#define DCD_EOF -1
+constexpr int DCD_EOF = -1;
 #define DCD_MAGIC 84
 #define DCD_IS_CHARMM 0x01
 #define DCD_HAS_4DIMS 0x02