diff --git a/NanoVNASaver/Formatting.py b/NanoVNASaver/Formatting.py
index d6646cb..b0d11f7 100644
--- a/NanoVNASaver/Formatting.py
+++ b/NanoVNASaver/Formatting.py
@@ -35,6 +35,7 @@ FMT_GROUP_DELAY = SITools.Format(max_nr_digits=5, space_str=" ")
 FMT_REACT = SITools.Format(max_nr_digits=5, space_str=" ", allow_strip=True)
 FMT_COMPLEX = SITools.Format(max_nr_digits=3, allow_strip=True,
                              printable_min=0, unprintable_under="- ")
+FMT_COMPLEX_NEG = SITools.Format(max_nr_digits=3, allow_strip=True)
 FMT_PARSE = SITools.Format(parse_sloppy_unit=True, parse_sloppy_kilo=True,
                            parse_clamp_min=0)
 
@@ -65,8 +66,8 @@ def format_gain(val: float, invert: bool = False) -> str:
     return f"{val:.3f} dB"
 
 
-def format_q_factor(val: float) -> str:
-    if val < 0 or val > 10000.0:
+def format_q_factor(val: float, allow_negative: bool = False) -> str:
+    if (not allow_negative and val < 0) or abs(val > 10000.0):
         return "\N{INFINITY}"
     return str(SITools.Value(val, fmt=FMT_Q_FACTOR))
 
@@ -79,8 +80,8 @@ def format_magnitude(val: float) -> str:
     return f"{val:.3f}"
 
 
-def format_resistance(val: float) -> str:
-    if val < 0:
+def format_resistance(val: float, allow_negative: bool = False) -> str:
+    if not allow_negative and val < 0:
         return "- \N{OHM SIGN}"
     return str(SITools.Value(val, "\N{OHM SIGN}", FMT_REACT))
 
@@ -105,8 +106,11 @@ def format_phase(val: float) -> str:
     return f"{math.degrees(val):.2f}\N{DEGREE SIGN}"
 
 
-def format_complex_imp(z: complex) -> str:
-    re = SITools.Value(z.real, fmt=FMT_COMPLEX)
+def format_complex_imp(z: complex, allow_negative: bool = False) -> str:
+    fmt_re = FMT_COMPLEX
+    if allow_negative:
+        fmt_re = FMT_COMPLEX_NEG
+    re = SITools.Value(z.real, fmt=fmt_re)
     im = SITools.Value(abs(z.imag), fmt=FMT_COMPLEX)
     return f"{re}{'-' if z.imag < 0 else '+'}j{im} \N{OHM SIGN}"