diff --git a/configure b/configure
index 4dccadf3d6..830602b9b3 100755
--- a/configure
+++ b/configure
@@ -5312,7 +5312,21 @@ if test x$GCC == xyes;  then
 
     *)
       WALLCXX="${WALLCXX} -Wstrict-null-sentinel"
-      WALLC="-std=gnu90 ${WALLC}"
+
+      if test x$tr_DARWIN != xyes;  then
+        WALLC="-std=gnu90 ${WALLC}"
+      fi
+      ;;
+  esac
+
+  case $CC in
+    *clang*)
+      ;;
+
+    *)
+      if test x$tr_DARWIN != xyes;  then
+        WALLC="-std=gnu90 ${WALLC}"
+      fi
       ;;
   esac
 
diff --git a/m4/configure.basics b/m4/configure.basics
index 02c7263c41..fb6e9330d9 100644
--- a/m4/configure.basics
+++ b/m4/configure.basics
@@ -100,7 +100,21 @@ if test x$GCC == xyes;  then
 
     *)
       WALLCXX="${WALLCXX} -Wstrict-null-sentinel"
-      WALLC="-std=gnu90 ${WALLC}"
+
+      if test x$tr_DARWIN != xyes;  then
+        WALLC="-std=gnu90 ${WALLC}"
+      fi
+      ;;
+  esac
+
+  case $CC in
+    *clang*)
+      ;;
+
+    *)
+      if test x$tr_DARWIN != xyes;  then
+        WALLC="-std=gnu90 ${WALLC}"
+      fi
       ;;
   esac