diff --git a/releasenotes.md b/releasenotes.md
index 9f9596c98..0bd482767 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -31,6 +31,7 @@
 - `@if` declarations were missing from -P output #1973.
 - Check exe and lib output so -o works with directories.
 - Swizzling an inline vector in a struct would cause a crash.
+- Fixed error and poor error message when using an invalid target name.
 
 ### Stdlib changes
 
diff --git a/src/build/libraries.c b/src/build/libraries.c
index 4c5559bdc..41ca9291a 100644
--- a/src/build/libraries.c
+++ b/src/build/libraries.c
@@ -111,7 +111,7 @@ static Library *add_library(JSONObject *object, const char *dir)
 	{
 		char *res = strdup(provides);
 		str_ellide_in_place(res, 32);
-		error_exit("Invalid 'provides' module name in %s, was '%s'.", library->dir, res);
+		error_exit("Invalid 'provides' module name in %s, was '%s', the name should only contain alphanumerical letters and '_'.", library->dir, res);
 	}
 	library->provides = provides;
 	library->execs = get_optional_string_array(context, object, "exec");
diff --git a/src/build/project.c b/src/build/project.c
index 59d97d2e1..ebe9d0e39 100644
--- a/src/build/project.c
+++ b/src/build/project.c
@@ -208,7 +208,7 @@ static void load_into_build_target(BuildParseContext context, JSONObject *json,
 		{
 			char *name_copy = strdup(name);
 			str_ellide_in_place(name_copy, 32);
-			error_exit("Error reading %s: invalid library target '%s'.", filename, name_copy);
+			error_exit("Error reading %s: invalid library target name '%s' – it should only contain alphanumerical letters and '_'.", context.file, name_copy);
 		}
 	}