diff --git a/scripts/nix-pull.in b/scripts/nix-pull.in
index efd0c074fd..e5c9cac536 100644
--- a/scripts/nix-pull.in
+++ b/scripts/nix-pull.in
@@ -74,7 +74,7 @@ print "$size store paths in manifest\n";
 # Register all substitutes.
 print STDERR "registering substitutes...\n";
 
-my $pid = open2(\*READ, \*WRITE, "$binDir/nix-store --substitute")
+my $pid = open2(\*READ, \*WRITE, "$binDir/nix-store --register-substitutes")
     or die "cannot run nix-store";
 
 close READ;
diff --git a/src/nix-store/help.txt b/src/nix-store/help.txt
index 30f94a0518..643c6bff58 100644
--- a/src/nix-store/help.txt
+++ b/src/nix-store/help.txt
@@ -9,7 +9,7 @@ Operations:
   --add / -A: copy a path to the Nix store
   --query / -q: query information
 
-  --substitute: register a substitute expression (dangerous!)
+  --register-substitutes: register a substitute expression (dangerous!)
   --clear-substitutes: clear all substitutes
   --register-validity: register path validity (dangerous!)
   --check-validity: check path validity
diff --git a/src/nix-store/main.cc b/src/nix-store/main.cc
index 4969246775..87fbe58b1b 100644
--- a/src/nix-store/main.cc
+++ b/src/nix-store/main.cc
@@ -394,7 +394,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
 }
 
 
-static void opSubstitute(Strings opFlags, Strings opArgs)
+static void opRegisterSubstitutes(Strings opFlags, Strings opArgs)
 {
     if (!opFlags.empty()) throw UsageError("unknown flag");
     if (!opArgs.empty()) throw UsageError("no arguments expected");
@@ -607,8 +607,8 @@ void run(Strings args)
             op = opPrintFixedPath;
         else if (arg == "--query" || arg == "-q")
             op = opQuery;
-        else if (arg == "--substitute")
-            op = opSubstitute;
+        else if (arg == "--register-substitutes")
+            op = opRegisterSubstitutes;
         else if (arg == "--clear-substitutes")
             op = opClearSubstitutes;
         else if (arg == "--register-validity")
diff --git a/tests/fallback.sh b/tests/fallback.sh
index 24e5784100..4a3d29f39e 100644
--- a/tests/fallback.sh
+++ b/tests/fallback.sh
@@ -5,7 +5,7 @@ outPath=$($TOP/src/nix-store/nix-store -q --fallback "$drvPath")
 echo "output path is $outPath"
 
 # Register a non-existant substitute
-(echo $outPath && echo "" && echo $TOP/no-such-program && echo 0 && echo 0) | $TOP/src/nix-store/nix-store --substitute
+(echo $outPath && echo "" && echo $TOP/no-such-program && echo 0 && echo 0) | $TOP/src/nix-store/nix-store --register-substitutes
 
 # Build the derivation
 $TOP/src/nix-store/nix-store -r --fallback "$drvPath"
diff --git a/tests/substitutes.sh b/tests/substitutes.sh
index cfc3fa71a1..150d6b8a3f 100644
--- a/tests/substitutes.sh
+++ b/tests/substitutes.sh
@@ -7,7 +7,7 @@ outPath=$($TOP/src/nix-store/nix-store -qvv "$drvPath")
 echo "output path is $outPath"
 
 regSub() {
-    (echo $1 && echo "" && echo $2 && echo 3 && echo $outPath && echo Hallo && echo Wereld && echo 0) | $TOP/src/nix-store/nix-store --substitute
+    (echo $1 && echo "" && echo $2 && echo 3 && echo $outPath && echo Hallo && echo Wereld && echo 0) | $TOP/src/nix-store/nix-store --register-substitutes
 }
 
 # Register a substitute for the output path.
diff --git a/tests/substitutes2.sh b/tests/substitutes2.sh
index 1a7b848ca3..6dcff6fd43 100644
--- a/tests/substitutes2.sh
+++ b/tests/substitutes2.sh
@@ -7,7 +7,7 @@ outPath=$($TOP/src/nix-store/nix-store -qvvvvv "$drvPath")
 echo "output path is $outPath"
 
 regSub() {
-    (echo $1 && echo "" && echo $2 && echo 3 && echo $outPath && echo Hallo && echo Wereld && echo 0) | $TOP/src/nix-store/nix-store --substitute
+    (echo $1 && echo "" && echo $2 && echo 3 && echo $outPath && echo Hallo && echo Wereld && echo 0) | $TOP/src/nix-store/nix-store --register-substitutes
 }
 
 # Register a substitute for the output path.