diff --git a/Source/cmNinjaNormalTargetGenerator.cxx b/Source/cmNinjaNormalTargetGenerator.cxx
index be7739e1a..cc49e39f4 100644
--- a/Source/cmNinjaNormalTargetGenerator.cxx
+++ b/Source/cmNinjaNormalTargetGenerator.cxx
@@ -495,7 +495,7 @@ void cmNinjaNormalTargetGenerator::WriteLinkStatement()
   int commandLineLengthLimit = 8000 - linkRuleLength;
 #elif defined(__linux) || defined(__APPLE__)
   // for instance ARG_MAX is 2096152 on Ubuntu or 262144 on Mac
-  int commandLineLengthLimit = sysconf(_SC_ARG_MAX) - linkRuleLength - 1000;
+  int commandLineLengthLimit = ((int)sysconf(_SC_ARG_MAX)) - linkRuleLength - 1000;
 #else
   int commandLineLengthLimit = -1;
 #endif