diff --git a/src/fix_ave_time.cpp b/src/fix_ave_time.cpp
index 481611a3cc..51e201000c 100644
--- a/src/fix_ave_time.cpp
+++ b/src/fix_ave_time.cpp
@@ -896,11 +896,34 @@ void FixAveTime::invoke_vector(bigint ntimestep)
 
   if (fp && me == 0) {
     if (overwrite) platform::fseek(fp,filepos);
-    fmt::print(fp,"{} {}\n",ntimestep,nrows);
-    for (i = 0; i < nrows; i++) {
-      fprintf(fp,"%d",i+1);
-      for (j = 0; j < nvalues; j++) fprintf(fp,format,array_total[i][j]/norm);
-      fprintf(fp,"\n");
+    if (yaml_flag) {
+      if (!yaml_header || overwrite) {
+        yaml_header = true;
+        fputs("keywords:\n - Step\n", fp);
+        bool first = true;
+        for (auto k : keyword) {
+          if (first) {
+            first = false;
+            fmt::print(fp, " - - '{}'\n", k);
+          } else fmt::print(fp, "   - '{}'\n", k);
+        }
+        fputs("data:\n", fp);
+      }
+      fmt::print(fp, "  {}:\n", ntimestep);
+      for (i = 0; i < nvalues; i++) {
+        for (j = 0; j < nrows; j++) {
+          if (j == 0) fputs("  - - ", fp);
+          else  fputs("    - ", fp);
+          fmt::print(fp,"{}\n",array_total[j][i]/norm);
+        }
+      }
+    } else {
+      fmt::print(fp,"{} {}\n",ntimestep,nrows);
+      for (i = 0; i < nrows; i++) {
+        fprintf(fp,"%d",i+1);
+        for (j = 0; j < nvalues; j++) fprintf(fp,format,array_total[i][j]/norm);
+        fprintf(fp,"\n");
+      }
     }
     fflush(fp);
     if (overwrite) {