diff --git a/generic/tkImgGIF.c b/generic/tkImgGIF.c
index 63689721c..a58f8204b 100644
--- a/generic/tkImgGIF.c
+++ b/generic/tkImgGIF.c
@@ -498,7 +498,13 @@ FileReadGIF(
      */
 
     if (Fread(gifConfPtr, buf, 1, 3, chan) != 3) {
-	return TCL_OK;
+	/*
+	 * Bug [865af0148c]: 3 bytes should be there, but data ended before
+	 */
+	Tcl_SetObjResult(interp, Tcl_NewStringObj(
+		"GIF file truncated", -1));
+	Tcl_SetErrorCode(interp, "TK", "IMAGE", "GIF", "TRUNCATED", NULL);
+	return TCL_ERROR;
     }
     bitPixel = 2 << (buf[0] & 0x07);
 
diff --git a/tests/corruptTruncatedColormap.gif b/tests/corruptTruncatedColormap.gif
new file mode 100644
index 000000000..21d4add9c
Binary files /dev/null and b/tests/corruptTruncatedColormap.gif differ
diff --git a/tests/imgPhoto.test b/tests/imgPhoto.test
index 29e6b530e..0a2cf7f96 100644
--- a/tests/imgPhoto.test
+++ b/tests/imgPhoto.test
@@ -1938,6 +1938,23 @@ test imgPhoto-20.6 {Reject truncated GIF (file)} -setup {
 } -cleanup {
     catch {image delete gif1}
 } -returnCodes error -result {error reading color map}
+test imgPhoto-20.6.1 {Reject truncated GIF in Colormap - ticket 865af0148c - file} -setup {
+    set fileName [file join [file dirname [info script]] corruptTruncatedColormap.gif]
+} -body {
+    image create photo gif1 -file $fileName
+} -cleanup {
+    catch {image delete gif1}
+} -returnCodes error -result {GIF file truncated}
+test imgPhoto-20.6.2 {Reject truncated GIF in Colormap - ticket 865af0148c - data} -setup {
+    set fileName [file join [file dirname [info script]] corruptTruncatedColormap.gif]
+    set h [open $fileName rb]
+    set d [read $h]
+    close $h
+} -body {
+    image create photo gif1 -data $d
+} -cleanup {
+    catch {image delete gif1}
+} -returnCodes error -result {GIF file truncated}
 test imgPhoto-20.7 {Reject corrupted GIF (> 4Gb) (binary string)} -constraints {
     nonPortable
 } -setup {