diff --git a/include/nlohmann/detail/input/binary_reader.hpp b/include/nlohmann/detail/input/binary_reader.hpp
index 73820a02c..9c606375a 100644
--- a/include/nlohmann/detail/input/binary_reader.hpp
+++ b/include/nlohmann/detail/input/binary_reader.hpp
@@ -2112,7 +2112,7 @@ class binary_reader
                 {
                     return false;
                 }
-                if (dim.size() == 1 || (dim.size() > 1 && dim.at(0) == 1)) // return normal array size if 1D row vector
+                if (dim.size() == 1 || (dim.size() == 2 && dim.at(0) == 1)) // return normal array size if 1D row vector
                 {
                     result = dim.at(dim.size() - 1);
                     return true;
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index a8a86e63c..3ac66c3a2 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -10488,7 +10488,7 @@ class binary_reader
                 {
                     return false;
                 }
-                if (dim.size() == 1 || (dim.size() > 1 && dim.at(0) == 1)) // return normal array size if 1D row vector
+                if (dim.size() == 1 || (dim.size() == 2 && dim.at(0) == 1)) // return normal array size if 1D row vector
                 {
                     result = dim.at(dim.size() - 1);
                     return true;