diff --git a/src/assign.c b/src/assign.c
index b114f0d4d..29f5dff4c 100644
--- a/src/assign.c
+++ b/src/assign.c
@@ -362,10 +362,9 @@ SEXP assign(SEXP dt, SEXP rows, SEXP cols, SEXP newcolnames, SEXP values)
   // cols : column names or numbers corresponding to the values to set
   // rows : row numbers to assign
   R_len_t numToDo, targetlen, vlen, oldncol, oldtncol, coln, protecti=0, newcolnum;
-  SEXP targetcol, nullint, s, colnam, tmp, key, index, a, assignedNames;
+  SEXP targetcol, nullint, colnam, tmp, key, index, assignedNames;
   bool verbose=GetVerbose();
   int ndelete=0;  // how many columns are being deleted
-  const char *c1, *tc1, *tc2;
   int *buf;
   if (isNull(dt)) error(_("assign has been passed a NULL dt"));
   if (TYPEOF(dt) != VECSXP) error(_("dt passed to %s isn't type VECSXP"), "assign");
diff --git a/src/dogroups.c b/src/dogroups.c
index 5d270ef4a..7fd1b956e 100644
--- a/src/dogroups.c
+++ b/src/dogroups.c
@@ -77,7 +77,7 @@ SEXP dogroups(SEXP dt, SEXP dtcols, SEXP groups, SEXP grpcols, SEXP jiscols, SEX
 {
   R_len_t ngrp, nrowgroups, njval=0, ngrpcols, ansloc=0, maxn, estn=-1, thisansloc, grpn, thislen, igrp;
   int nprotect=0;
-  SEXP ans=NULL, jval, thiscol, BY, N, I, GRP, iSD, xSD, s, RHS, target, source;
+  SEXP ans=NULL, jval, thiscol, BY, N, I, GRP, iSD, xSD, RHS, target, source;
   Rboolean wasvector, firstalloc=FALSE, NullWarnDone=FALSE;
   const bool verbose = LOGICAL(verboseArg)[0]==1;
   double tstart=0, tblock[10]={0}; int nblock[10]={0}; // For verbose printing, tstart is updated each block