diff --git a/dlls/d3d9/device.c b/dlls/d3d9/device.c
index 1938016cf30..0d288264cd3 100644
--- a/dlls/d3d9/device.c
+++ b/dlls/d3d9/device.c
@@ -2884,7 +2884,7 @@ static HRESULT WINAPI d3d9_device_SetVertexShaderConstantB(IDirect3DDevice9Ex *i
     TRACE("iface %p, reg_idx %u, data %p, count %u.\n", iface, reg_idx, data, count);
 
     wined3d_mutex_lock();
-    hr = wined3d_device_set_vs_consts_b(device->wined3d_device, reg_idx, data, count);
+    hr = wined3d_device_set_vs_consts_b(device->wined3d_device, reg_idx, count, data);
     wined3d_mutex_unlock();
 
     return hr;
diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index 316be5d2d6e..ec489e944f2 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -2374,24 +2374,28 @@ static void device_invalidate_shader_constants(const struct wined3d_device *devi
 }
 
 HRESULT CDECL wined3d_device_set_vs_consts_b(struct wined3d_device *device,
-        UINT start_register, const BOOL *constants, UINT bool_count)
+        unsigned int start_idx, unsigned int count, const BOOL *constants)
 {
-    UINT count = min(bool_count, WINED3D_MAX_CONSTS_B - start_register);
-    UINT i;
+    unsigned int i;
 
-    TRACE("device %p, start_register %u, constants %p, bool_count %u.\n",
-            device, start_register, constants, bool_count);
+    TRACE("device %p, start_idx %u, count %u, constants %p.\n",
+            device, start_idx, count, constants);
 
-    if (!constants || start_register >= WINED3D_MAX_CONSTS_B)
+    if (!constants || start_idx >= WINED3D_MAX_CONSTS_B)
         return WINED3DERR_INVALIDCALL;
 
-    memcpy(&device->update_state->vs_consts_b[start_register], constants, count * sizeof(BOOL));
-    for (i = 0; i < count; ++i)
-        TRACE("Set BOOL constant %u to %s.\n", start_register + i, constants[i] ? "true" : "false");
+    if (count > WINED3D_MAX_CONSTS_B - start_idx)
+        count = WINED3D_MAX_CONSTS_B - start_idx;
+    memcpy(&device->update_state->vs_consts_b[start_idx], constants, count * sizeof(*constants));
+    if (TRACE_ON(d3d))
+    {
+        for (i = 0; i < count; ++i)
+            TRACE("Set BOOL constant %u to %#x.\n", start_idx + i, constants[i]);
+    }
 
     if (device->recording)
     {
-        for (i = start_register; i < count + start_register; ++i)
+        for (i = start_idx; i < count + start_idx; ++i)
             device->recording->changed.vertexShaderConstantsB |= (1u << i);
     }
     else
diff --git a/dlls/wined3d/stateblock.c b/dlls/wined3d/stateblock.c
index a57591b5b62..d5a7c617903 100644
--- a/dlls/wined3d/stateblock.c
+++ b/dlls/wined3d/stateblock.c
@@ -911,7 +911,7 @@ void CDECL wined3d_stateblock_apply(const struct wined3d_stateblock *stateblock)
     for (i = 0; i < stateblock->num_contained_vs_consts_b; ++i)
     {
         wined3d_device_set_vs_consts_b(device, stateblock->contained_vs_consts_b[i],
-                stateblock->state.vs_consts_b + stateblock->contained_vs_consts_b[i], 1);
+                1, &stateblock->state.vs_consts_b[stateblock->contained_vs_consts_b[i]]);
     }
 
     apply_lights(device, &stateblock->state);
diff --git a/dlls/wined3d/wined3d.spec b/dlls/wined3d/wined3d.spec
index c4446b85720..24951208368 100644
--- a/dlls/wined3d/wined3d.spec
+++ b/dlls/wined3d/wined3d.spec
@@ -149,7 +149,7 @@
 @ cdecl wined3d_device_set_vertex_shader(ptr ptr)
 @ cdecl wined3d_device_set_viewport(ptr ptr)
 @ cdecl wined3d_device_set_vs_cb(ptr long ptr)
-@ cdecl wined3d_device_set_vs_consts_b(ptr long ptr long)
+@ cdecl wined3d_device_set_vs_consts_b(ptr long long ptr)
 @ cdecl wined3d_device_set_vs_consts_f(ptr long long ptr)
 @ cdecl wined3d_device_set_vs_consts_i(ptr long long ptr)
 @ cdecl wined3d_device_set_vs_resource_view(ptr long ptr)
diff --git a/include/wine/wined3d.h b/include/wine/wined3d.h
index af320a47bcb..202047574e5 100644
--- a/include/wine/wined3d.h
+++ b/include/wine/wined3d.h
@@ -2247,7 +2247,7 @@ void __cdecl wined3d_device_set_vertex_shader(struct wined3d_device *device, str
 void __cdecl wined3d_device_set_viewport(struct wined3d_device *device, const struct wined3d_viewport *viewport);
 void __cdecl wined3d_device_set_vs_cb(struct wined3d_device *device, UINT idx, struct wined3d_buffer *buffer);
 HRESULT __cdecl wined3d_device_set_vs_consts_b(struct wined3d_device *device,
-        UINT start_register, const BOOL *constants, UINT bool_count);
+        unsigned int start_idx, unsigned int count, const BOOL *constants);
 HRESULT __cdecl wined3d_device_set_vs_consts_f(struct wined3d_device *device,
         unsigned int start_idx, unsigned int count, const struct wined3d_vec4 *constants);
 HRESULT __cdecl wined3d_device_set_vs_consts_i(struct wined3d_device *device,