diff --git a/src/compiler/nir/nir_opt_large_constants.c b/src/compiler/nir/nir_opt_large_constants.c
index 6ef6593b870..537bd1c96ea 100644
--- a/src/compiler/nir/nir_opt_large_constants.c
+++ b/src/compiler/nir/nir_opt_large_constants.c
@@ -533,6 +533,12 @@ nir_opt_large_constants(nir_shader *shader,
 
    nir_builder b = nir_builder_create(impl);
 
+   /* We must preserve signed zero and disallow e.g. fma fusion
+    * when we create new floating point instructions because it's not
+    * even clear the result is only used as float.
+    */
+   b.fp_math_ctrl = nir_fp_exact | nir_fp_preserve_signed_zero;
+
    nir_foreach_block(block, impl) {
       nir_foreach_instr_safe(instr, block) {
          if (instr->type == nir_instr_type_deref) {
diff --git a/src/compiler/nir/tests/opt_large_constants_tests.cpp b/src/compiler/nir/tests/opt_large_constants_tests.cpp
index f8e010c7330..4605a34c693 100644
--- a/src/compiler/nir/tests/opt_large_constants_tests.cpp
+++ b/src/compiler/nir/tests/opt_large_constants_tests.cpp
@@ -208,7 +208,7 @@ TEST_F(nir_large_constants_test, small_float_natural_numbers_including_zero_arra
           32    %4 = ushr %1 (0x76543210), %3
           32    %5 = load_const (0x0000000f = 15)
           32    %6 = iand %4, %5 (0xf)
-          32    %7 = u2f32 %6
+          32    %7 = u2f32 %6 // exact, preserve:sz
                      @use (%7)
                      // succs: b1
           block b1: