diff --git a/src/video_core/renderer_opengl/gl_shader_gen.cpp b/src/video_core/renderer_opengl/gl_shader_gen.cpp
index c4dad2c32..90553cc7f 100644
--- a/src/video_core/renderer_opengl/gl_shader_gen.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_gen.cpp
@@ -1841,7 +1841,7 @@ struct Vertex {
         if (attrib < config.gs_output_attributes) {
             return fmt::format("vtx.attributes[{}].{}", attrib, "xyzw"[comp]);
         }
-        return "0.0";
+        return "1.0";
     };
 
     out += "const float EPSILON_Z = 0.00000001f;\n\n";
diff --git a/src/video_core/renderer_vulkan/vk_shader_gen.cpp b/src/video_core/renderer_vulkan/vk_shader_gen.cpp
index 37aac4dd9..59fd56a8c 100644
--- a/src/video_core/renderer_vulkan/vk_shader_gen.cpp
+++ b/src/video_core/renderer_vulkan/vk_shader_gen.cpp
@@ -1810,7 +1810,7 @@ layout (set = 0, binding = 0, std140) uniform vs_config {
             if (attrib < config.gs_output_attributes) {
                 return fmt::format("vs_out_attr{}.{}", attrib, "xyzw"[comp]);
             }
-            return "0.0";
+            return "1.0";
         };
 
         out += "const float EPSILON_Z = 0.00000001f;\n\n";
@@ -1900,7 +1900,7 @@ struct Vertex {
         if (attrib < config.gs_output_attributes) {
             return fmt::format("vtx.attributes[{}].{}", attrib, "xyzw"[comp]);
         }
-        return "0.0";
+        return "1.0";
     };
 
     out += "const float EPSILON_Z = 0.00000001f;\n\n";
diff --git a/src/video_core/shader/shader.cpp b/src/video_core/shader/shader.cpp
index 126efd834..b8393c379 100644
--- a/src/video_core/shader/shader.cpp
+++ b/src/video_core/shader/shader.cpp
@@ -44,6 +44,10 @@ OutputVertex OutputVertex::FromAttributeBuffer(const RasterizerRegs& regs,
         std::array<f24, 32> vertex_slots_overflow;
     };
 
+    // Some games use attributes without setting them in GPUREG_SH_OUTMAP_Oi
+    // Hardware tests have shown that they are initialized to 1.f in this case.
+    vertex_slots_overflow.fill(f24::One());
+
     // Assert that OutputVertex has enough space for 24 semantic registers
     static_assert(sizeof(std::array<f24, 24>) == sizeof(ret),
                   "Struct and array have different sizes.");