diff --git a/src/panfrost/bifrost/valhall/test/test-lower-constants.cpp b/src/panfrost/bifrost/valhall/test/test-lower-constants.cpp
index 6bd3293c995..8438ebd0537 100644
--- a/src/panfrost/bifrost/valhall/test/test-lower-constants.cpp
+++ b/src/panfrost/bifrost/valhall/test/test-lower-constants.cpp
@@ -188,3 +188,16 @@ TEST_F(LowerConstants, HandleTrickyNegativesFP16)
    CASE(bi_fadd_v2f16_to(b, bi_register(0), bi_register(0), bi_imm_f16(57216.0)),
         bi_fadd_v2f16_to(b, bi_register(0), bi_register(0), bi_neg(bi_half(va_lut(3), 1))));
 }
+
+TEST_F(LowerConstants, MaintainMkvecRestrictedSwizzles)
+{
+   CASE(bi_mkvec_v2i8_to(b, bi_register(0), bi_register(0),
+                         bi_imm_u8(0), bi_imm_u32(0)),
+        bi_mkvec_v2i8_to(b, bi_register(0), bi_register(0),
+                         bi_byte(va_lut(0), 0), va_lut(0)));
+
+   CASE(bi_mkvec_v2i8_to(b, bi_register(0), bi_register(0),
+                         bi_imm_u8(14), bi_imm_u32(0)),
+        bi_mkvec_v2i8_to(b, bi_register(0), bi_register(0),
+                         bi_byte(va_lut(11), 2), va_lut(0)));
+}
diff --git a/src/panfrost/bifrost/valhall/va_lower_constants.c b/src/panfrost/bifrost/valhall/va_lower_constants.c
index f8dc9d37a8f..e5a8fd7e224 100644
--- a/src/panfrost/bifrost/valhall/va_lower_constants.c
+++ b/src/panfrost/bifrost/valhall/va_lower_constants.c
@@ -143,7 +143,7 @@ va_resolve_constant(bi_builder *b, uint32_t value, struct va_src_info info, bool
    }
 
    /* Try extending a byte */
-   if (!staging && (info.widen || info.lanes) &&
+   if (!staging && (info.widen || info.lanes || info.lane) &&
        is_extension_of_8(value, is_signed)) {
 
       bi_index lut = va_lut_index_8(value & 0xFF);
@@ -207,7 +207,7 @@ va_lower_constants(bi_context *ctx, bi_instr *I)
          } else if (info.size == VA_SIZE_16) {
             assert(swz >= BI_SWIZZLE_H00 && swz <= BI_SWIZZLE_H11);
             value = bi_apply_swizzle(value, swz);
-         } else if (info.size == VA_SIZE_8 && info.lanes) {
+         } else if (info.size == VA_SIZE_8 && (info.lane || info.lanes)) {
             /* 8-bit extract */
             unsigned chan = (swz - BI_SWIZZLE_B0000);
             assert(chan < 4);
@@ -221,6 +221,16 @@ va_lower_constants(bi_context *ctx, bi_instr *I)
          bi_index cons = va_resolve_constant(&b, value, info, is_signed, staging);
          cons.neg ^= I->src[s].neg;
          I->src[s] = cons;
+
+         /* If we're selecting a single 8-bit lane, we should return a single
+          * 8-bit lane to ensure the result is encodeable. By convention,
+          * applying the lane select puts the desired constant (at least) in the
+          * bottom byte, so we can always select the bottom byte.
+          */
+         if (info.lane && I->src[s].swizzle == BI_SWIZZLE_H01) {
+            assert(info.size == VA_SIZE_8);
+            I->src[s] = bi_byte(I->src[s], 0);
+         }
       }
    }
 }