diff --git a/mission/controller/acs/Guidance.cpp b/mission/controller/acs/Guidance.cpp
index cc0a20d9..538d4e35 100644
--- a/mission/controller/acs/Guidance.cpp
+++ b/mission/controller/acs/Guidance.cpp
@@ -159,7 +159,7 @@ void Guidance::targetQuatPtgGs(timeval timeAbsolute, const double timeDelta,
   }
 
   // normalize weights for convenience
-  double normFactor = 1. / (std::abs(sunWeight) + std::abs(earthWeight));
+  double normFactor = 1. / (std::fabs(sunWeight) + std::fabs(earthWeight));
   sunWeight *= normFactor;
   earthWeight *= normFactor;