diff --git a/include/gnss_utils/utils/chisquare_ci.h b/include/gnss_utils/utils/chisquare_ci.h
index 83274b542cb81868f651f3ccf41bca2ad445caa4..c6f31488a3a0cdfa5ab82565d64ed0424ebc6747 100644
--- a/include/gnss_utils/utils/chisquare_ci.h
+++ b/include/gnss_utils/utils/chisquare_ci.h
@@ -13,7 +13,7 @@
 namespace GnssUtils
 {
 
-double chisq2ci(double chisq, int dof)
+inline double chisq2ci(double chisq, int dof)
 {
     assert(dof > 0);
 
@@ -33,7 +33,7 @@ double chisq2ci(double chisq, int dof)
     return lower->second + (chisq - lower->first) / (upper->first - lower->first) * (upper->second - lower->second);
 };
 
-double ci2chisq(double ci, int dof)
+inline double ci2chisq(double ci, int dof)
 {
     assert(dof > 0);