diff --git a/renderdoc/driver/d3d11/d3d11_overlay.cpp b/renderdoc/driver/d3d11/d3d11_overlay.cpp
index d14108fb5..b735feac8 100644
--- a/renderdoc/driver/d3d11/d3d11_overlay.cpp
+++ b/renderdoc/driver/d3d11/d3d11_overlay.cpp
@@ -556,7 +556,7 @@ ResourceId D3D11Replay::RenderOverlay(ResourceId texid, FloatVector clearCol, De
 
     m_pImmediateContext->RSSetState(rs);
 
-    CheckerboardCBuffer pixelData = {0};
+    CheckerboardCBuffer pixelData = {};
 
     UINT dummy = 1;
     D3D11_VIEWPORT views[D3D11_VIEWPORT_AND_SCISSORRECT_OBJECT_COUNT_PER_PIPELINE] = {0};
@@ -824,7 +824,7 @@ ResourceId D3D11Replay::RenderOverlay(ResourceId texid, FloatVector clearCol, De
 
     D3D11_VIEWPORT view = m_pImmediateContext->GetCurrentPipelineState()->RS.Viewports[0];
 
-    Vec4f viewport = Vec4f(view.Width, view.Height);
+    Vec4f viewport = Vec4f(view.Width, view.Height, 0.0f, 0.0f);
     ID3D11Buffer *gsbuf = GetDebugManager()->MakeCBuffer(&viewport.x, sizeof(viewport));
 
     for(size_t i = 0; i < events.size(); i++)
diff --git a/renderdoc/driver/d3d11/d3d11_rendermesh.cpp b/renderdoc/driver/d3d11/d3d11_rendermesh.cpp
index e191317a1..37861f6de 100644
--- a/renderdoc/driver/d3d11/d3d11_rendermesh.cpp
+++ b/renderdoc/driver/d3d11/d3d11_rendermesh.cpp
@@ -326,7 +326,7 @@ void D3D11Replay::RenderMesh(uint32_t eventId, const rdcarray<MeshFormat> &secon
 
       pixelData.MeshDisplayFormat = MESHDISPLAY_SOLID;
       pixelData.MeshColour =
-          Vec4f(cfg.position.meshColor.x, cfg.position.meshColor.y, cfg.position.meshColor.z);
+          Vec4f(cfg.position.meshColor.x, cfg.position.meshColor.y, cfg.position.meshColor.z, 0.0f);
       GetDebugManager()->FillCBuffer(psCBuf, &pixelData, sizeof(pixelData));
       m_pImmediateContext->PSSetConstantBuffers(0, 1, &psCBuf);
 
diff --git a/renderdoc/driver/d3d12/d3d12_overlay.cpp b/renderdoc/driver/d3d12/d3d12_overlay.cpp
index 6568b7a71..b1d27c683 100644
--- a/renderdoc/driver/d3d12/d3d12_overlay.cpp
+++ b/renderdoc/driver/d3d12/d3d12_overlay.cpp
@@ -1515,7 +1515,7 @@ ResourceId D3D12Replay::RenderOverlay(ResourceId texid, FloatVector clearCol, De
 
       list->SetGraphicsRootSignature(m_General.CheckerboardRootSig);
 
-      CheckerboardCBuffer pixelData = {0};
+      CheckerboardCBuffer pixelData = {};
 
       pixelData.BorderWidth = 3;
       pixelData.CheckerSquareDimension = 16.0f;
@@ -1683,7 +1683,7 @@ ResourceId D3D12Replay::RenderOverlay(ResourceId texid, FloatVector clearCol, De
         Vec4f viewport;
 
         if(!rs.views.empty())
-          viewport = Vec4f(rs.views[0].Width, rs.views[0].Height);
+          viewport = Vec4f(rs.views[0].Width, rs.views[0].Height, 0.0f, 0.0f);
 
         D3D12RenderState::SignatureElement viewportElem(eRootCBV, ResourceId(), 0);
         WrappedID3D12Resource::GetResIDFromAddr(
diff --git a/renderdoc/driver/gl/gl_overlay.cpp b/renderdoc/driver/gl/gl_overlay.cpp
index 7f12dfc16..e1817e2d0 100644
--- a/renderdoc/driver/gl/gl_overlay.cpp
+++ b/renderdoc/driver/gl/gl_overlay.cpp
@@ -1628,7 +1628,7 @@ ResourceId GLReplay::RenderOverlay(ResourceId texid, FloatVector clearCol, Debug
       return ResourceId();
     }
 
-    *v = Vec4f(rs.Viewports[0].width, rs.Viewports[0].height);
+    *v = Vec4f(rs.Viewports[0].width, rs.Viewports[0].height, 0.0f, 0.0f);
     drv.glUnmapBuffer(eGL_COPY_WRITE_BUFFER);
 
     rdcarray<uint32_t> events = passEvents;
diff --git a/renderdoc/driver/vulkan/vk_overlay.cpp b/renderdoc/driver/vulkan/vk_overlay.cpp
index 49a93eef9..8328b28ba 100644
--- a/renderdoc/driver/vulkan/vk_overlay.cpp
+++ b/renderdoc/driver/vulkan/vk_overlay.cpp
@@ -3327,7 +3327,7 @@ ResourceId VulkanReplay::RenderOverlay(ResourceId texid, FloatVector clearCol, D
         Vec4f *ubo = (Vec4f *)m_Overlay.m_TriSizeUBO.Map(&viewOffs);
         if(!ubo)
           return ResourceId();
-        *ubo = Vec4f(state.views[0].width, state.views[0].height);
+        *ubo = Vec4f(state.views[0].width, state.views[0].height, 0.0f, 0.0f);
         m_Overlay.m_TriSizeUBO.Unmap();
 
         uint32_t offsets[2] = {meshOffs, viewOffs};
diff --git a/renderdoc/maths/vec.h b/renderdoc/maths/vec.h
index 30ab7ed40..179cc6c36 100644
--- a/renderdoc/maths/vec.h
+++ b/renderdoc/maths/vec.h
@@ -34,11 +34,12 @@
 
 struct Vec2f
 {
-  Vec2f(float X = 0.0f, float Y = 0.0f)
+  Vec2f(float X, float Y)
   {
     x = X;
     y = Y;
   }
+  Vec2f() { x = y = 0.0f; }
 
   union
   {
@@ -53,7 +54,8 @@ struct Vec2f
 class Vec3f
 {
 public:
-  Vec3f(const float X = 0.0f, const float Y = 0.0f, const float Z = 0.0f) : x(X), y(Y), z(Z) {}
+  Vec3f(const float X, const float Y, const float Z) : x(X), y(Y), z(Z) {}
+  Vec3f() { x = y = z = 0.0f; }
   inline float Dot(const Vec3f &o) const { return x * o.x + y * o.y + z * o.z; }
   inline Vec3f Cross(const Vec3f &o) const
   {
@@ -83,13 +85,14 @@ struct FloatVector;
 
 struct Vec4f
 {
-  Vec4f(float X = 0.0f, float Y = 0.0f, float Z = 0.0f, float W = 0.0f)
+  Vec4f(float X, float Y, float Z, float W)
   {
     x = X;
     y = Y;
     z = Z;
     w = W;
   }
+  Vec4f() { x = y = z = w = 0.0f; }
   Vec4f(const FloatVector &v);
   operator Vec3f() const { return Vec3f(x, y, z); }
   operator FloatVector() const;
@@ -169,11 +172,12 @@ inline Vec4f operator+=(Vec4f &a, const Vec4f &b)
 
 struct Vec2u
 {
-  Vec2u(uint32_t X = 0, uint32_t Y = 0)
+  Vec2u(uint32_t X, uint32_t Y)
   {
     x = X;
     y = Y;
   }
+  Vec2u() { x = y = 0; }
   union
   {
     struct
@@ -186,13 +190,14 @@ struct Vec2u
 
 struct Vec4u
 {
-  Vec4u(uint32_t X = 0, uint32_t Y = 0, uint32_t Z = 0, uint32_t W = 0)
+  Vec4u(uint32_t X, uint32_t Y, uint32_t Z, uint32_t W)
   {
     x = X;
     y = Y;
     z = Z;
     w = W;
   }
+  Vec4u() { x = y = z = w = 0; }
   union
   {
     struct
@@ -205,12 +210,13 @@ struct Vec4u
 
 struct Vec3u
 {
-  Vec3u(uint32_t X = 0, uint32_t Y = 0, uint32_t Z = 0)
+  Vec3u(uint32_t X, uint32_t Y, uint32_t Z)
   {
     x = X;
     y = Y;
     z = Z;
   }
+  Vec3u() { x = y = z = 0; }
   union
   {
     struct
@@ -223,13 +229,14 @@ struct Vec3u
 
 struct Vec4i
 {
-  Vec4i(int32_t X = 0, int32_t Y = 0, int32_t Z = 0, int32_t W = 0)
+  Vec4i(int32_t X, int32_t Y, int32_t Z, int32_t W)
   {
     x = X;
     y = Y;
     z = Z;
     w = W;
   }
+  Vec4i() { x = y = z = w = 0; }
   union
   {
     struct
diff --git a/renderdoc/replay/replay_controller.cpp b/renderdoc/replay/replay_controller.cpp
index 552d229ff..c8602b9cc 100644
--- a/renderdoc/replay/replay_controller.cpp
+++ b/renderdoc/replay/replay_controller.cpp
@@ -1144,7 +1144,7 @@ ResultDetails ReplayController::SaveTexture(const TextureSave &saveData, const r
 
         if(sd.alpha != AlphaMapping::Discard)
         {
-          Vec4f col = Vec4f(sd.alphaCol.x, sd.alphaCol.y, sd.alphaCol.z);
+          Vec4f col = Vec4f(sd.alphaCol.x, sd.alphaCol.y, sd.alphaCol.z, 0.0f);
           if(sd.alpha == AlphaMapping::BlendToCheckerboard)
           {
             bool lightSquare = ((x / 64) % 2) == ((y / 64) % 2);