diff --git a/Makefile b/Makefile
index b4c54087d6..6374e79add 100644
--- a/Makefile
+++ b/Makefile
@@ -358,10 +358,12 @@ ifeq ($(CXX_BUILD), 1)
    CFLAGS += -std=c++0x -xc++ -D__STDC_CONSTANT_MACROS
 else
    LD = $(CC)
-   ifneq ($(findstring icc,$(CC)),)
-      CFLAGS += -std=c99 -D_GNU_SOURCE
-   else
-      CFLAGS += -std=gnu99
+   ifneq ($(GNU90_BUILD), 1)
+      ifneq ($(findstring icc,$(CC)),)
+         CFLAGS += -std=c99 -D_GNU_SOURCE
+      else
+         CFLAGS += -std=gnu99
+      endif
    endif
 endif
 
diff --git a/Makefile.win b/Makefile.win
index 3bb63ff8e2..f6ed9754b8 100644
--- a/Makefile.win
+++ b/Makefile.win
@@ -257,7 +257,9 @@ CXXFLAGS += -Wall -Wno-unused-result -Wno-unused-variable -I. -std=c++0x -D__STD
 ifeq ($(CXX_BUILD), 1)
    CFLAGS += -std=c++0x -xc++ -D__STDC_CONSTANT_MACROS
 else
-   CFLAGS += -std=gnu99
+   ifneq ($(GNU90_BUILD), 1)
+      CFLAGS += -std=gnu99
+   endif
 endif
 
 all: $(TARGET) $(JTARGET)