diff --git a/main.cpp b/main.cpp
index 39bbb49..63f07b0 100644
--- a/main.cpp
+++ b/main.cpp
@@ -9,7 +9,8 @@
 
 #define DOMAIN_RE "(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,}"
 // https://docs.joinmastodon.org/methods/accounts/#422-unprocessable-entity
-#define USERNAME_RE "[a-zA-Z0-9_]+"
+// https://akko.erincandescent.net/@postmaster-emeritus
+#define USERNAME_RE "[a-zA-Z0-9\\-_]+"
 #define ACCT_RE USERNAME_RE "(?:@" DOMAIN_RE ")?"
 
 int main(int argc, char** argv) {
diff --git a/models.cpp b/models.cpp
index 0c66ea6..6ccd2b8 100644
--- a/models.cpp
+++ b/models.cpp
@@ -9,7 +9,8 @@
 
 #define DOMAIN_RE "(?:[a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,}"
 // https://docs.joinmastodon.org/methods/accounts/#422-unprocessable-entity
-#define USERNAME_RE "[a-zA-Z0-9_]+"
+// https://akko.erincandescent.net/@postmaster-emeritus
+#define USERNAME_RE "[a-zA-Z0-9\\-_]+"
 
 using json = nlohmann::json;
 static time_t parse_rfc3339(const std::string& str);