diff --git a/tests/json_fmt.cpp b/tests/json_fmt.cpp
index aa9da9c..77ac4b0 100644
--- a/tests/json_fmt.cpp
+++ b/tests/json_fmt.cpp
@@ -76,6 +76,7 @@ int main() {
       {"0.02", {0.02, ""}},
       {"0.002", {0.002, ""}},
       {"1e+0000", {1., ""}},
+      {"1e-0000", {1., ""}},
       {"0e-2", {0., ""}},
       {"1e", {1., "e"}},
       {"1e+", {1., "e+"}},