diff --git a/src/gallium/drivers/radeonsi/si_shader_nir.c b/src/gallium/drivers/radeonsi/si_shader_nir.c
index 4f44e968f83..d410a6c2d66 100644
--- a/src/gallium/drivers/radeonsi/si_shader_nir.c
+++ b/src/gallium/drivers/radeonsi/si_shader_nir.c
@@ -446,21 +446,35 @@ void si_nir_scan_shader(const struct nir_shader *nir,
 		}
 
 		i = variable->data.driver_location;
-		if (processed_outputs & ((uint64_t)1 << i))
-			continue;
-
-		processed_outputs |= ((uint64_t)1 << i);
-		num_outputs++;
-
-		info->output_semantic_name[i] = semantic_name;
-		info->output_semantic_index[i] = semantic_index;
-		info->output_usagemask[i] = TGSI_WRITEMASK_XYZW;
 
 		unsigned num_components = 4;
 		unsigned vector_elements = glsl_get_vector_elements(glsl_without_array(variable->type));
 		if (vector_elements)
 			num_components = vector_elements;
 
+		if (glsl_type_is_64bit(glsl_without_array(variable->type)))
+			num_components = MIN2(num_components * 2, 4);
+
+		ubyte usagemask = 0;
+		for (unsigned j = 0; j < num_components; j++) {
+			switch (j + variable->data.location_frac) {
+				case 0:
+					usagemask |= TGSI_WRITEMASK_X;
+					break;
+				case 1:
+					usagemask |= TGSI_WRITEMASK_Y;
+					break;
+				case 2:
+					usagemask |= TGSI_WRITEMASK_Z;
+					break;
+				case 3:
+					usagemask |= TGSI_WRITEMASK_W;
+					break;
+				default:
+					unreachable("error calculating component index");
+			}
+		}
+
 		unsigned gs_out_streams;
 		if (variable->data.stream & (1u << 31)) {
 			gs_out_streams = variable->data.stream & ~(1u << 31);
@@ -476,23 +490,39 @@ void si_nir_scan_shader(const struct nir_shader *nir,
 		unsigned streamz = (gs_out_streams >> 4) & 3;
 		unsigned streamw = (gs_out_streams >> 6) & 3;
 
-		if (info->output_usagemask[i] & TGSI_WRITEMASK_X) {
+		if (usagemask & TGSI_WRITEMASK_X) {
+			info->output_usagemask[i] |= TGSI_WRITEMASK_X;
 			info->output_streams[i] |= streamx;
 			info->num_stream_output_components[streamx]++;
 		}
-		if (info->output_usagemask[i] & TGSI_WRITEMASK_Y) {
+		if (usagemask & TGSI_WRITEMASK_Y) {
+			info->output_usagemask[i] |= TGSI_WRITEMASK_Y;
 			info->output_streams[i] |= streamy << 2;
 			info->num_stream_output_components[streamy]++;
 		}
-		if (info->output_usagemask[i] & TGSI_WRITEMASK_Z) {
+		if (usagemask & TGSI_WRITEMASK_Z) {
+			info->output_usagemask[i] |= TGSI_WRITEMASK_Z;
 			info->output_streams[i] |= streamz << 4;
 			info->num_stream_output_components[streamz]++;
 		}
-		if (info->output_usagemask[i] & TGSI_WRITEMASK_W) {
+		if (usagemask & TGSI_WRITEMASK_W) {
+			info->output_usagemask[i] |= TGSI_WRITEMASK_W;
 			info->output_streams[i] |= streamw << 6;
 			info->num_stream_output_components[streamw]++;
 		}
 
+		/* make sure we only count this location once against the
+		 * num_outputs counter.
+		 */
+		if (processed_outputs & ((uint64_t)1 << i))
+			continue;
+
+		processed_outputs |= ((uint64_t)1 << i);
+		num_outputs++;
+
+		info->output_semantic_name[i] = semantic_name;
+		info->output_semantic_index[i] = semantic_index;
+
 		switch (semantic_name) {
 		case TGSI_SEMANTIC_PRIMID:
 			info->writes_primid = true;