diff --git a/src/core/internal/dassert.d b/src/core/internal/dassert.d
index 1be8297870..af6fadb1a1 100644
--- a/src/core/internal/dassert.d
+++ b/src/core/internal/dassert.d
@@ -88,7 +88,15 @@ private string miniFormat(V)(const ref V v)
     else static if (__traits(isFloating, V))
     {
         char[60] val;
-        const len = sprintf(&val[0], "%g", v);
+        int len;
+        static if (is(V == cfloat) || is(V == cdouble))
+            len = sprintf(&val[0], "%g + %gi", v.re, v.im);
+        else static if (is(V == creal))
+            len = sprintf(&val[0], "%Lg + %Lgi", v.re, v.im);
+        else static if (is(V == real) || is(V == ireal))
+            len = sprintf(&val[0], "%Lg", v);
+        else
+            len = sprintf(&val[0], "%g", v);
         return val.idup[0 .. len];
     }
     // special-handling for void-arrays
diff --git a/src/gc/impl/conservative/gc.d b/src/gc/impl/conservative/gc.d
index 2e7f951ffb..6e4ba5417c 100644
--- a/src/gc/impl/conservative/gc.d
+++ b/src/gc/impl/conservative/gc.d
@@ -4023,7 +4023,7 @@ debug(PRINTF_TO_FILE)
                 gcStartTick = MonoTime.currTime;
             immutable timeElapsed = MonoTime.currTime - gcStartTick;
             immutable secondsAsDouble = timeElapsed.total!"hnsecs" / cast(double)convert!("seconds", "hnsecs")(1);
-            len = fprintf(gcx_fh, "%10.6lf: ", secondsAsDouble);
+            len = fprintf(gcx_fh, "%10.6f: ", secondsAsDouble);
         }
         len += fprintf(gcx_fh, fmt, args);
         fflush(gcx_fh);