diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index 078a7d173..405ccd0a0 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -14366,7 +14366,7 @@ test(2002.12, rbind(DT1, DT2, idcol='id'),     data.table(id=integer(), a=logica
 
 #rbindlist coverage
 test(2003.1, rbindlist(list(), use.names=1), error="use.names= should be TRUE, FALSE, or not used [(]\"check\" by default[)]")
-test(2003.2, rbindlist(list(), fill=1), error="fill= should be TRUE or FALSE")
+test(2003.2, rbindlist(list(), fill=1), error="fill should be TRUE or FALSE")
 test(2003.3, rbindlist(list(data.table(a=1:2), data.table(b=3:4)), fill=TRUE, use.names=FALSE),
              data.table(a=c(1:4)))
 test(2003.4, rbindlist(list(data.table(a=1:2,c=5:6), data.table(b=3:4)), fill=TRUE, use.names=FALSE),
diff --git a/src/fastmean.c b/src/fastmean.c
index 2fcc6ebd2..1c9b3eb64 100644
--- a/src/fastmean.c
+++ b/src/fastmean.c
@@ -36,7 +36,7 @@ SEXP fastmean(SEXP args)
   if (length(args)>2) {
     tmp = CADDR(args);
     if (!isLogical(tmp) || LENGTH(tmp)!=1 || LOGICAL(tmp)[0]==NA_LOGICAL)
-      error(_("narm should be TRUE or FALSE"));  // # nocov ; [.data.table should construct the .External call correctly
+      error(_("%s should be TRUE or FALSE"), "narm");  // # nocov ; [.data.table should construct the .External call correctly
     narm=LOGICAL(tmp)[0];
   }
   PROTECT(ans = allocNAVector(REALSXP, 1));
diff --git a/src/nafill.c b/src/nafill.c
index 03aa6d091..5fe81933d 100644
--- a/src/nafill.c
+++ b/src/nafill.c
@@ -100,7 +100,7 @@ SEXP nafillR(SEXP obj, SEXP type, SEXP fill, SEXP nan_is_na_arg, SEXP inplace, S
 
   bool binplace = LOGICAL(inplace)[0];
   if (!IS_TRUE_OR_FALSE(nan_is_na_arg))
-    error(_("nan_is_na must be TRUE or FALSE")); // # nocov
+    error(_("%s must be TRUE or FALSE"), "nan_is_na"); // # nocov
   bool nan_is_na = LOGICAL(nan_is_na_arg)[0];
 
   SEXP x = R_NilValue;
diff --git a/src/rbindlist.c b/src/rbindlist.c
index ba19d2c38..d8cd32476 100644
--- a/src/rbindlist.c
+++ b/src/rbindlist.c
@@ -5,7 +5,7 @@
 SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg)
 {
   if (!isLogical(fillArg) || LENGTH(fillArg) != 1 || LOGICAL(fillArg)[0] == NA_LOGICAL)
-    error(_("fill= should be TRUE or FALSE"));
+    error(_("%s should be TRUE or FALSE"), "fill");
   if (!isLogical(usenamesArg) || LENGTH(usenamesArg)!=1)
     error(_("use.names= should be TRUE, FALSE, or not used (\"check\" by default)"));  // R levels converts "check" to NA
   if (!length(l)) return(l);