diff --git a/src/compiler/nir/nir_lower_mediump.c b/src/compiler/nir/nir_lower_mediump.c
index 83d5f82ccc5..4bd7e8f488c 100644
--- a/src/compiler/nir/nir_lower_mediump.c
+++ b/src/compiler/nir/nir_lower_mediump.c
@@ -476,9 +476,7 @@ static bool
 const_is_f16(nir_scalar scalar)
 {
    double value = nir_scalar_as_float(scalar);
-   uint16_t fp16_val = _mesa_float_to_half(value);
-   bool is_denorm = (fp16_val & 0x7fff) != 0 && (fp16_val & 0x7fff) <= 0x3ff;
-   return value == _mesa_half_to_float(fp16_val) && !is_denorm;
+   return _mesa_float_is_half(value);
 }
 
 static bool
diff --git a/src/util/half_float.h b/src/util/half_float.h
index cc49251d229..c7234212e71 100644
--- a/src/util/half_float.h
+++ b/src/util/half_float.h
@@ -129,6 +129,21 @@ _mesa_half_is_negative(uint16_t h)
    return !!(h & 0x8000);
 }
 
+static inline bool
+_mesa_float_is_half(double val)
+{
+   /* val parameter is double to prevent implicit double->float cast.  We have
+    * to cast to float because that's what _mesa_float_to_half expects and we
+    * don't have any readily available _double_to_half function.  This may
+    * introduce double-rounding errors, however this is ok because the final
+    * check is done at double precision, any rounding will fail to produce the
+    * original value.
+    */
+   uint16_t fp16_val = _mesa_float_to_half((float) val);
+   bool is_denorm = (fp16_val & 0x7fff) != 0 && (fp16_val & 0x7fff) <= 0x3ff;
+   return val == (double) _mesa_half_to_float(fp16_val) && !is_denorm;
+}
+
 
 #ifdef __cplusplus