diff --git a/DESCRIPTION b/DESCRIPTION
index 4b601cec..5bbf8f77 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,8 +1,8 @@
 Package: useeior
 Type: Package
 Title: USEEIO R modeling software
-Version: 1.5.2
-Date: 2024-6-14
+Version: 1.5.3
+Date: 2024-7-13
 Authors@R: c(
   person("Ben","Young", email="ben.young@erg.com", role="aut"),
   person("Jorge","Vendries", email="jvendries@gmail.com", role="aut"),
diff --git a/R/BuildModel.R b/R/BuildModel.R
index b2020ef2..d5693f59 100644
--- a/R/BuildModel.R
+++ b/R/BuildModel.R
@@ -229,6 +229,12 @@ createCfromFactorsandBflows <- function(factors,B_flows) {
   flows_inBnotC <- setdiff(B_flows, colnames(C))
   C[, flows_inBnotC] <- 0
   C[is.na(C)] <- 0
+
+  if("Greenhouse Gases" %in% factors$Indicator) {
+    # Make sure CO2e flows are characterized (see issue #281)
+    f <- B_flows[!(B_flows %in% factors$Flow) & grepl("kg CO2e", B_flows)]
+    C["Greenhouse Gases", f] <- 1
+  }
   # Filter and resort model C flows and make it into a matrix
   C <- as.matrix(C[, B_flows])
   return(C)