diff --git a/src/assign.c b/src/assign.c
index fc960132d..3356e918b 100644
--- a/src/assign.c
+++ b/src/assign.c
@@ -527,7 +527,7 @@ SEXP assign(SEXP dt, SEXP rows, SEXP cols, SEXP newcolnames, SEXP values)
       targetcol = VECTOR_ELT(dt,coln);
     }
     const char *ret = memrecycle(targetcol, rows, 0, targetlen, thisvalue, 0, -1, coln+1, CHAR(STRING_ELT(names, coln)));
-    if (ret) warning(ret);
+    if (ret) warning("%s", ret);
   }
 
   *_Last_updated = numToDo;  // the updates have taken place with no error, so update .Last.updated now
diff --git a/src/forder.c b/src/forder.c
index 8a62e1de7..c9063782b 100644
--- a/src/forder.c
+++ b/src/forder.c
@@ -56,7 +56,7 @@ static int *anso = NULL;
 static bool notFirst=false;
 
 static char msg[1001];
-#define STOP(...) do {snprintf(msg, 1000, __VA_ARGS__); cleanup(); error(msg);} while(0)      // http://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html#Swallowing-the-Semicolon
+#define STOP(...) do {snprintf(msg, 1000, __VA_ARGS__); cleanup(); error("%s", msg);} while(0)      // http://gcc.gnu.org/onlinedocs/cpp/Swallowing-the-Semicolon.html#Swallowing-the-Semicolon
 // use STOP in this file (not error()) to ensure cleanup() is called first
 // snprintf to msg first in case nrow (just as an example) is provided in the message because cleanup() sets nrow to 0
 #undef warning
diff --git a/src/fwrite.c b/src/fwrite.c
index ef8b822e9..322909749 100644
--- a/src/fwrite.c
+++ b/src/fwrite.c
@@ -736,7 +736,7 @@ void fwriteMain(fwriteMainArgs args)
     }
     if (f==-1) {
       *ch = '\0';
-      DTPRINT(buff);
+      DTPRINT("%s", buff);
       free(buff);
     } else {
       int ret1=0, ret2=0;
@@ -926,7 +926,7 @@ void fwriteMain(fwriteMainArgs args)
           errno=0;
           if (f==-1) {
             *ch='\0';  // standard C string end marker so DTPRINT knows where to stop
-            DTPRINT(myBuff);
+            DTPRINT("%s", myBuff);
           } else if ((args.is_gzip ? WRITE(f, myzBuff, (int)myzbuffUsed)
                                    : WRITE(f, myBuff,  (int)(ch-myBuff))) == -1) {
             failed=true;         // # nocov
diff --git a/src/rbindlist.c b/src/rbindlist.c
index 366902883..2ffff3af8 100644
--- a/src/rbindlist.c
+++ b/src/rbindlist.c
@@ -208,7 +208,7 @@ SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg)
           const char *str = isString(s) ? CHAR(STRING_ELT(s,w2)) : "";
           snprintf(buff, 1000, _("Column %d ['%s'] of item %d is missing in item %d. Use fill=TRUE to fill with NA (NULL for list columns), or use.names=FALSE to ignore column names.%s"),
                         w2+1, str, i+1, missi+1, extra );
-          if (usenames==TRUE) error(buff);
+          if (usenames==TRUE) error("%s", buff);
           i = LENGTH(l); // break from outer i loop
           break;         // break from inner j loop
         }
@@ -229,8 +229,8 @@ SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg)
         }
         const char *o = isNull(opt) ? "message" : CHAR(STRING_ELT(opt,0));
         if      (strcmp(o,"message")==0) { eval(PROTECT(lang2(install("message"),PROTECT(ScalarString(mkChar(buff))))), R_GlobalEnv); UNPROTECT(2); }
-        else if (strcmp(o,"warning")==0) warning(buff);
-        else if (strcmp(o,"error")==0)   error(buff);
+        else if (strcmp(o,"warning")==0) warning("%s", buff);
+        else if (strcmp(o,"error")==0)   error("%s", buff);
         else if (strcmp(o,"none")!=0)    warning(_("options()$datatable.rbindlist.check=='%s' which is not 'message'|'warning'|'error'|'none'. See news item 5 in v1.12.2."), o);
       }
     }
@@ -490,7 +490,7 @@ SEXP rbindlist(SEXP l, SEXP usenamesArg, SEXP fillArg, SEXP idcolArg)
       }
       for (int k=0; k<nLevel; ++k) SET_TRUELENGTH(levelsRaw[k], 0);
       savetl_end();
-      if (warnStr[0]) warning(warnStr);  // now savetl_end() has happened it's safe to call warning (could error if options(warn=2))
+      if (warnStr[0]) warning("%s", warnStr);  // now savetl_end() has happened it's safe to call warning (could error if options(warn=2))
       SEXP levelsSxp;
       setAttrib(target, R_LevelsSymbol, levelsSxp=allocVector(STRSXP, nLevel));
       for (int k=0; k<nLevel; ++k) SET_STRING_ELT(levelsSxp, k, levelsRaw[k]);
diff --git a/src/subset.c b/src/subset.c
index 215845179..d3513a775 100644
--- a/src/subset.c
+++ b/src/subset.c
@@ -281,7 +281,7 @@ SEXP subsetDT(SEXP x, SEXP rows, SEXP cols) { // API change needs update NEWS.md
     SEXP max = PROTECT(ScalarInteger(nrow)); nprotect++;
     rows = PROTECT(convertNegAndZeroIdx(rows, max, ScalarLogical(TRUE), ScalarLogical(TRUE))); nprotect++;
     const char *err = check_idx(rows, nrow, &anyNA, &orderedSubset);
-    if (err!=NULL) error(err);
+    if (err!=NULL) error("%s", err);
   }
 
   if (!isInteger(cols)) error(_("Internal error. Argument '%s' to %s is type '%s' not '%s'"), "cols", "Csubset", type2char(TYPEOF(cols)), "integer"); // # nocov