diff --git a/packages/graphile-build-pg/src/plugins/PgConditionComputedColumnPlugin.js b/packages/graphile-build-pg/src/plugins/PgConditionComputedColumnPlugin.js
index 8bdd1259e..968195ca7 100644
--- a/packages/graphile-build-pg/src/plugins/PgConditionComputedColumnPlugin.js
+++ b/packages/graphile-build-pg/src/plugins/PgConditionComputedColumnPlugin.js
@@ -21,7 +21,7 @@ function getCompatibleComputedColumns(build, table) {
     const { pseudoColumnName } = computedColumnDetails;
 
     // Must have only one required argument
-    const nonOptionalArgumentsCount = proc.argDefaultsNum - proc.inputArgsCount;
+    const nonOptionalArgumentsCount = proc.inputArgsCount - proc.argDefaultsNum;
     if (nonOptionalArgumentsCount > 1) {
       return memo;
     }
diff --git a/packages/graphile-build-pg/src/plugins/PgOrderComputedColumnsPlugin.js b/packages/graphile-build-pg/src/plugins/PgOrderComputedColumnsPlugin.js
index 7ba59ea0f..36bdb6cc8 100644
--- a/packages/graphile-build-pg/src/plugins/PgOrderComputedColumnsPlugin.js
+++ b/packages/graphile-build-pg/src/plugins/PgOrderComputedColumnsPlugin.js
@@ -41,7 +41,7 @@ export default (function PgOrderComputedColumnsPlugin(builder) {
 
           // Must have only one required argument
           const nonOptionalArgumentsCount =
-            proc.argDefaultsNum - proc.inputArgsCount;
+            proc.inputArgsCount - proc.argDefaultsNum;
           if (nonOptionalArgumentsCount > 1) {
             return memo;
           }
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/defaultOptions.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/defaultOptions.test.js.snap
index 527322695..044f3ea4c 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/defaultOptions.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/defaultOptions.test.js.snap
@@ -6213,6 +6213,8 @@ type Post implements Node {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -6323,6 +6325,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -6412,6 +6417,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   HEADLINE_ASC
@@ -16192,6 +16199,8 @@ type Post implements Node {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -16302,6 +16311,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -16391,6 +16403,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   HEADLINE_ASC
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/function-clash.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/function-clash.test.js.snap
index c54f63aa0..116788e75 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/function-clash.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/function-clash.test.js.snap
@@ -6213,6 +6213,8 @@ type Post implements Node {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -6323,6 +6325,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -6412,6 +6417,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   HEADLINE_ASC
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/indexes.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/indexes.test.js.snap
index 8101a20dc..953835bd0 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/indexes.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/indexes.test.js.snap
@@ -6458,6 +6458,8 @@ type Post implements Node {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -6562,6 +6564,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`authorId\` field.\\"\\"\\"
   authorId: Int
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`id\` field.\\"\\"\\"
   id: Int
 }
@@ -6641,6 +6646,8 @@ type PostsEdge {
 enum PostsOrderBy {
   AUTHOR_ID_ASC
   AUTHOR_ID_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ID_ASC
   ID_DESC
   NATURAL
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/inflect-core.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/inflect-core.test.js.snap
index 4d4a9c6d4..b8ce2f81f 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/inflect-core.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/inflect-core.test.js.snap
@@ -6213,6 +6213,8 @@ type Post implements N {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -6323,6 +6325,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -6412,6 +6417,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   HEADLINE_ASC
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/pgColumnFilter.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/pgColumnFilter.test.js.snap
index 506dee42c..6f20ea1fa 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/pgColumnFilter.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/pgColumnFilter.test.js.snap
@@ -2313,6 +2313,8 @@ type Post implements Node {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headlineTrimmed(length: Int, omission: String): String
   headlineTrimmedNoDefaults(length: Int, omission: String): String
@@ -2358,6 +2360,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -2442,6 +2447,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   ID_ASC
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/rbac.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/rbac.test.js.snap
index 2bc08baac..a4c682935 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/rbac.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/rbac.test.js.snap
@@ -7528,6 +7528,8 @@ type Post implements Node {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -7638,6 +7640,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -7727,6 +7732,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   HEADLINE_ASC
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/simplePrint.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/simplePrint.test.js.snap
index e1ff92f93..dc7af1924 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/simplePrint.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/simplePrint.test.js.snap
@@ -6256,6 +6256,8 @@ type Post implements Node {
     after: Cursor
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   headlineTrimmed(length: Int, omission: String): String
   headlineTrimmedNoDefaults(length: Int, omission: String): String
   headlineTrimmedStrict(length: Int, omission: String): String
@@ -6302,6 +6304,9 @@ input PostCondition {
 
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
+
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
 }
 
 \\"\\"\\"An input for mutations affecting \`Post\`\\"\\"\\"
@@ -6390,6 +6395,8 @@ enum PostsOrderBy {
   ENUMS_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   PRIMARY_KEY_ASC
   PRIMARY_KEY_DESC
 }
diff --git a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/skipNodePlugin.test.js.snap b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/skipNodePlugin.test.js.snap
index 8e1ea7808..906693e04 100644
--- a/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/skipNodePlugin.test.js.snap
+++ b/packages/postgraphile-core/__tests__/integration/schema/__snapshots__/skipNodePlugin.test.js.snap
@@ -5599,6 +5599,8 @@ type Post {
     offset: Int
   ): PostComputedIntervalSetConnection!
   computedTextArray: [String]
+  computedWithOptionalArg(i: Int): Int
+  computedWithRequiredArg(i: Int!): Int
   enums: [AnEnum]
   headline: String!
   headlineTrimmed(length: Int, omission: String): String
@@ -5704,6 +5706,9 @@ input PostCondition {
   \\"\\"\\"Checks for equality with the object’s \`comptypes\` field.\\"\\"\\"
   comptypes: [ComptypeInput]
 
+  \\"\\"\\"Checks for equality with the object’s \`computedWithOptionalArg\` field.\\"\\"\\"
+  computedWithOptionalArg: Int
+
   \\"\\"\\"Checks for equality with the object’s \`enums\` field.\\"\\"\\"
   enums: [AnEnum]
 
@@ -5793,6 +5798,8 @@ enum PostsOrderBy {
   BODY_DESC
   COMPTYPES_ASC
   COMPTYPES_DESC
+  COMPUTED_WITH_OPTIONAL_ARG_ASC
+  COMPUTED_WITH_OPTIONAL_ARG_DESC
   ENUMS_ASC
   ENUMS_DESC
   HEADLINE_ASC
diff --git a/packages/postgraphile-core/__tests__/kitchen-sink-schema.sql b/packages/postgraphile-core/__tests__/kitchen-sink-schema.sql
index 3df6fea5a..ea8dbc817 100644
--- a/packages/postgraphile-core/__tests__/kitchen-sink-schema.sql
+++ b/packages/postgraphile-core/__tests__/kitchen-sink-schema.sql
@@ -358,6 +358,10 @@ create function a.post_computed_compound_type_array(post a.post, object c.compou
 create function a.post_computed_text_array(post a.post) returns text[] as $$ select ARRAY['str1','str2','str3']; $$ language sql stable;
 create function a.post_computed_interval_array(post a.post) returns interval[] as $$ select ARRAY[interval '12 seconds', interval '3 hours', interval '34567 seconds']; $$ language sql stable;
 create function a.post_computed_interval_set(post a.post) returns setof interval as $$ begin return next interval '12 seconds'; return next interval '3 hours'; return next interval '34567 seconds'; end; $$ language plpgsql stable;
+create function a.post_computed_with_required_arg(post a.post, i int) returns int as $$ select 1; $$ language sql stable strict;
+comment on function a.post_computed_with_required_arg(post a.post, i int) is E'@sortable\n@filterable';
+create function a.post_computed_with_optional_arg(post a.post, i int = 1) returns int as $$ select 1; $$ language sql stable strict;
+comment on function a.post_computed_with_optional_arg(post a.post, i int) is E'@sortable\n@filterable';
 
 -- Procs -> custom mutations
 create function a.mutation_compound_type_array(object c.compound_type) returns c.compound_type[] as $$ select ARRAY[object, (null, null, null, null, null, null, null, null)::c.compound_type, (object.a + 1, object.b, object.c, object.d, object.e, object.f, object.g, object.foo_bar)::c.compound_type]; $$ language sql volatile;