diff --git a/src/makeg95.env b/src/makeg95.env
index af4b7e129a..a87b513ddf 100644
--- a/src/makeg95.env
+++ b/src/makeg95.env
@@ -81,7 +81,9 @@ RCDEFSWITCH=--define
 # but commenting out RCPREPROCESSOR then does the trick.
 #RCPREPROCESSOR=--preprocessor "$(CC) -c -E -xc-header -DRC_INVOKED"
 
-RESFLAGS=$(RCPREPROCESSOR) $(RCINCSWITCH) $(WXDIR)/include $(RCINCSWITCH) $(WXDIR)/contrib/include $(RCDEFSWITCH) __WIN32__ $(RCDEFSWITCH) __WIN95__ $(RCDEFSWITCH) __GNUWIN32__
+# Don't make this too long (e.g. by adding contrib/include/wx) because it will
+# truncate the command line
+RESFLAGS=$(RCPREPROCESSOR) $(RCINCSWITCH) $(WXDIR)/include $(RCDEFSWITCH) __WIN32__ $(RCDEFSWITCH) __WIN95__ $(RCDEFSWITCH) __GNUWIN32__
 
 # Needed to build a DLL if your linker does not support --shared option.
 AS = $(CROSS)as