diff --git a/docs/source/stubtest.rst b/docs/source/stubtest.rst
index a8279eb6c239..f3c036f56c06 100644
--- a/docs/source/stubtest.rst
+++ b/docs/source/stubtest.rst
@@ -42,7 +42,7 @@ test Python's official collection of library stubs,
 `typeshed <https://github.com/python/typeshed>`_.
 
 .. warning::
-    
+
     stubtest will import and execute Python code from the packages it checks.
 
 Example
@@ -69,7 +69,7 @@ Here's a quick example of what stubtest can do:
     error: library.foo is inconsistent, runtime argument "x" has a default value but stub argument does not
     Stub: at line 3
     def (x: builtins.int)
-    Runtime: at line 3 in file ~/library.py
+    Runtime: in file ~/library.py:3
     def (x=None)
 
     error: library.x variable differs from runtime type Literal['hello, stubtest']
diff --git a/mypy/stubtest.py b/mypy/stubtest.py
index 4a99c407f319..cd173f63e2a1 100644
--- a/mypy/stubtest.py
+++ b/mypy/stubtest.py
@@ -129,10 +129,10 @@ def get_description(self, concise: bool = False) -> str:
             stub_file = stub_node.path or None
 
         stub_loc_str = ""
-        if stub_line:
-            stub_loc_str += f" at line {stub_line}"
         if stub_file:
             stub_loc_str += f" in file {Path(stub_file)}"
+        if stub_line:
+            stub_loc_str += f"{':' if stub_file else ' at line '}{stub_line}"
 
         runtime_line = None
         runtime_file = None
@@ -147,10 +147,10 @@ def get_description(self, concise: bool = False) -> str:
                 pass
 
         runtime_loc_str = ""
-        if runtime_line:
-            runtime_loc_str += f" at line {runtime_line}"
         if runtime_file:
             runtime_loc_str += f" in file {Path(runtime_file)}"
+        if runtime_line:
+            runtime_loc_str += f"{':' if runtime_file else ' at line '}{runtime_line}"
 
         output = [
             _style("error: ", color="red", bold=True),
diff --git a/mypy/test/data.py b/mypy/test/data.py
index 535ebf304784..6e2ad198f614 100644
--- a/mypy/test/data.py
+++ b/mypy/test/data.py
@@ -169,9 +169,7 @@ def parse_test_case(case: DataDrivenTestCase) -> None:
         elif item.id == "triggered" and item.arg is None:
             triggered = item.data
         else:
-            raise ValueError(
-                f"Invalid section header {item.id} in {case.file} at line {item.line}"
-            )
+            raise ValueError(f"Invalid section header {item.id} in {case.file}:{item.line}")
 
     if out_section_missing:
         raise ValueError(f"{case.file}, line {first_item.line}: Required output section not found")
diff --git a/mypy/test/teststubtest.py b/mypy/test/teststubtest.py
index 42dd40d76414..6bb4dfb2c937 100644
--- a/mypy/test/teststubtest.py
+++ b/mypy/test/teststubtest.py
@@ -1561,9 +1561,9 @@ def test_output(self) -> None:
         expected = (
             f'error: {TEST_MODULE_NAME}.bad is inconsistent, stub argument "number" differs '
             'from runtime argument "num"\n'
-            f"Stub: at line 1 in file {TEST_MODULE_NAME}.pyi\n"
+            f"Stub: in file {TEST_MODULE_NAME}.pyi:1\n"
             "def (number: builtins.int, text: builtins.str)\n"
-            f"Runtime: at line 1 in file {TEST_MODULE_NAME}.py\ndef (num, text)\n\n"
+            f"Runtime: in file {TEST_MODULE_NAME}.py:1\ndef (num, text)\n\n"
             "Found 1 error (checked 1 module)\n"
         )
         assert remove_color_code(output) == expected
@@ -1721,7 +1721,7 @@ def test_config_file(self) -> None:
         output = run_stubtest(stub=stub, runtime=runtime, options=[])
         assert remove_color_code(output) == (
             f"error: {TEST_MODULE_NAME}.temp variable differs from runtime type Literal[5]\n"
-            f"Stub: at line 2 in file {TEST_MODULE_NAME}.pyi\n_decimal.Decimal\nRuntime:\n5\n\n"
+            f"Stub: in file {TEST_MODULE_NAME}.pyi:2\n_decimal.Decimal\nRuntime:\n5\n\n"
             "Found 1 error (checked 1 module)\n"
         )
         output = run_stubtest(stub=stub, runtime=runtime, options=[], config_file=config_file)