diff --git a/dlls/d3d8/device.c b/dlls/d3d8/device.c
index 21de2d6bea8..ed953fe6b16 100644
--- a/dlls/d3d8/device.c
+++ b/dlls/d3d8/device.c
@@ -2746,7 +2746,7 @@ static HRESULT WINAPI d3d8_device_GetPixelShaderConstant(IDirect3DDevice8 *iface
             iface, start_register, data, count);
 
     wined3d_mutex_lock();
-    hr = wined3d_device_get_ps_consts_f(device->wined3d_device, start_register, data, count);
+    hr = wined3d_device_get_ps_consts_f(device->wined3d_device, start_register, count, data);
     wined3d_mutex_unlock();
 
     return hr;
diff --git a/dlls/d3d9/device.c b/dlls/d3d9/device.c
index ce67292c5fa..b0ef7240620 100644
--- a/dlls/d3d9/device.c
+++ b/dlls/d3d9/device.c
@@ -3124,7 +3124,8 @@ static HRESULT WINAPI d3d9_device_GetPixelShaderConstantF(IDirect3DDevice9Ex *if
     TRACE("iface %p, reg_idx %u, data %p, count %u.\n", iface, reg_idx, data, count);
 
     wined3d_mutex_lock();
-    hr = wined3d_device_get_ps_consts_f(device->wined3d_device, reg_idx, data, count);
+    hr = wined3d_device_get_ps_consts_f(device->wined3d_device,
+            reg_idx, count, (struct wined3d_vec4 *)data);
     wined3d_mutex_unlock();
 
     return hr;
diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index 9af2b70ff55..e0a73707a93 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -2722,18 +2722,18 @@ HRESULT CDECL wined3d_device_set_ps_consts_f(struct wined3d_device *device,
 }
 
 HRESULT CDECL wined3d_device_get_ps_consts_f(const struct wined3d_device *device,
-        UINT start_register, float *constants, UINT vector4f_count)
+        unsigned int start_idx, unsigned int count, struct wined3d_vec4 *constants)
 {
     const struct wined3d_d3d_info *d3d_info = &device->adapter->d3d_info;
-    int count = min(vector4f_count, d3d_info->limits.ps_uniform_count - start_register);
 
-    TRACE("device %p, start_register %u, constants %p, vector4f_count %u.\n",
-            device, start_register, constants, vector4f_count);
+    TRACE("device %p, start_idx %u, count %u, constants %p.\n",
+            device, start_idx, count, constants);
 
-    if (!constants || count < 0)
+    if (!constants || start_idx >= d3d_info->limits.ps_uniform_count
+            || count > d3d_info->limits.ps_uniform_count - start_idx)
         return WINED3DERR_INVALIDCALL;
 
-    memcpy(constants, &device->state.ps_consts_f[start_register], count * sizeof(float) * 4);
+    memcpy(constants, &device->state.ps_consts_f[start_idx], count * sizeof(*constants));
 
     return WINED3D_OK;
 }
diff --git a/dlls/wined3d/wined3d.spec b/dlls/wined3d/wined3d.spec
index 42039f69e8b..4eb24702e90 100644
--- a/dlls/wined3d/wined3d.spec
+++ b/dlls/wined3d/wined3d.spec
@@ -71,7 +71,7 @@
 @ cdecl wined3d_device_get_primitive_type(ptr ptr)
 @ cdecl wined3d_device_get_ps_cb(ptr long)
 @ cdecl wined3d_device_get_ps_consts_b(ptr long ptr long)
-@ cdecl wined3d_device_get_ps_consts_f(ptr long ptr long)
+@ cdecl wined3d_device_get_ps_consts_f(ptr long long ptr)
 @ cdecl wined3d_device_get_ps_consts_i(ptr long ptr long)
 @ cdecl wined3d_device_get_ps_resource_view(ptr long)
 @ cdecl wined3d_device_get_ps_sampler(ptr long)
diff --git a/include/wine/wined3d.h b/include/wine/wined3d.h
index 5eea88427fa..4cfe1e00660 100644
--- a/include/wine/wined3d.h
+++ b/include/wine/wined3d.h
@@ -2117,7 +2117,7 @@ struct wined3d_buffer * __cdecl wined3d_device_get_ps_cb(const struct wined3d_de
 HRESULT __cdecl wined3d_device_get_ps_consts_b(const struct wined3d_device *device,
         UINT start_register, BOOL *constants, UINT bool_count);
 HRESULT __cdecl wined3d_device_get_ps_consts_f(const struct wined3d_device *device,
-        UINT start_register, float *constants, UINT vector4f_count);
+        unsigned int start_idx, unsigned int count, struct wined3d_vec4 *constants);
 HRESULT __cdecl wined3d_device_get_ps_consts_i(const struct wined3d_device *device,
         UINT start_register, int *constants, UINT vector4i_count);
 struct wined3d_shader_resource_view * __cdecl wined3d_device_get_ps_resource_view(const struct wined3d_device *device,