diff --git a/cli/src/template.pest b/cli/src/template.pest
index d73cddc59..232bd4542 100644
--- a/cli/src/template.pest
+++ b/cli/src/template.pest
@@ -25,8 +25,8 @@ raw_literal = @{ literal_char+ }
 literal = { "\"" ~ (raw_literal | escape)* ~ "\"" }
 
 integer_literal = {
-  ASCII_NONZERO_DIGIT ~ ASCII_DIGIT*
-  | "0"
+  "-"? ~ ASCII_NONZERO_DIGIT ~ ASCII_DIGIT*
+  | "-"? ~ "0"
 }
 
 identifier = @{ (ASCII_ALPHA | "_") ~ (ASCII_ALPHANUMERIC | "_")* }
diff --git a/cli/tests/test_log_command.rs b/cli/tests/test_log_command.rs
index 0973f1f96..0f2ce72b0 100644
--- a/cli/tests/test_log_command.rs
+++ b/cli/tests/test_log_command.rs
@@ -632,6 +632,16 @@ fn test_log_shortest_length_parameter() {
     @  2
     ◉  0
     "###);
+    insta::assert_snapshot!(
+        test_env.jj_cmd_success(&repo_path, &["log", "-T", "commit_id.shortest(-0)"]), @r###"
+    @  2
+    ◉  0
+    "###);
+    insta::assert_snapshot!(
+        test_env.jj_cmd_success(&repo_path, &["log", "-T", "commit_id.shortest(-100)"]), @r###"
+    @  2
+    ◉  0
+    "###);
     insta::assert_snapshot!(
         test_env.jj_cmd_success(&repo_path, &["log", "-T", "commit_id.shortest(100)"]), @r###"
     @  230dd059e1b059aefc0da06a2e5a7dbf22362f22
diff --git a/cli/tests/test_templater.rs b/cli/tests/test_templater.rs
index 4d6a8b0c1..401a5728b 100644
--- a/cli/tests/test_templater.rs
+++ b/cli/tests/test_templater.rs
@@ -164,6 +164,14 @@ fn test_templater_parse_error() {
       |
       = Method "foo" doesn't exist for type "Integer"
     "###);
+    insta::assert_snapshot!(render_err(r#"(-empty)"#), @r###"
+    Error: Failed to parse template:  --> 1:2
+      |
+    1 | (-empty)
+      |  ^---
+      |
+      = expected template
+    "###);
 
     insta::assert_snapshot!(render_err(r#"("foo" ++ "bar").baz()"#), @r###"
     Error: Failed to parse template:  --> 1:18
@@ -516,6 +524,66 @@ fn test_templater_fill_function() {
     over the lazy dog
     "###);
 
+    // A low value will not chop words, but can chop a label by words
+    insta::assert_snapshot!(
+        render(r#"fill(9, "Longlonglongword an some short words " ++
+                       label("error", "longlonglongword and short words") ++ " back out\n")"#),
+        @r###"
+    Longlonglongword
+    an some
+    short
+    words
+    longlonglongword
+    and short
+    words
+    back out
+    "###);
+
+    // Filling to 0 means breaking at every word
+    insta::assert_snapshot!(
+        render(r#"fill(0, "The quick fox jumps over the " ++
+                       label("error", "lazy") ++ " dog\n")"#),
+        @r###"
+    The
+    quick
+    fox
+    jumps
+    over
+    the
+    lazy
+    dog
+    "###);
+
+    // Filling to -0 is the same as 0
+    insta::assert_snapshot!(
+        render(r#"fill(-0, "The quick fox jumps over the " ++
+                       label("error", "lazy") ++ " dog\n")"#),
+        @r###"
+    The
+    quick
+    fox
+    jumps
+    over
+    the
+    lazy
+    dog
+    "###);
+
+    // Filling to negatives are clamped to the same as zero
+    insta::assert_snapshot!(
+        render(r#"fill(-10, "The quick fox jumps over the " ++
+                       label("error", "lazy") ++ " dog\n")"#),
+        @r###"
+    The
+    quick
+    fox
+    jumps
+    over
+    the
+    lazy
+    dog
+    "###);
+
     // Word-wrap, then indent
     insta::assert_snapshot!(
         render(r#""START marker to help insta\n" ++