diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9a8b827..7ea4b77 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -24,7 +24,7 @@ All notable changes to this project will be documented in this file.
     - default Docker ARG variables 
     - add '$' as a trigger character 
 - textDocument/hover
-  - HEALTHCHECK CMD flags ([#82](https://github.com/rcjsuen/dockerfile-language-server-nodejs/issues/82))
+  - HEALTHCHECK CMD flags ([#82](https://github.com/rcjsuen/dockerfile-language-server-nodejs/issues/82), [#104](https://github.com/rcjsuen/dockerfile-language-server-nodejs/issues/104))
 - textDocument/publishDiagnostics
   - check the spelling of instruction flags ([#75](https://github.com/rcjsuen/dockerfile-language-server-nodejs/issues/75))
     - COPY's from
diff --git a/src/dockerHover.ts b/src/dockerHover.ts
index 29a2f80..57408c8 100644
--- a/src/dockerHover.ts
+++ b/src/dockerHover.ts
@@ -91,23 +91,54 @@ export class DockerHover {
 				}
 			}
 
-			if (instruction.getKeyword() === "HEALTHCHECK") {
-				let flags = (instruction as ModifiableInstruction).getFlags();
-				for (let flag of flags) {
-					if (Util.isInsideRange(textDocumentPosition.position, flag.getNameRange())) {
-						switch (flag.getName()) {
-							case "interval":
-								return this.markdown.getMarkdown("HEALTHCHECK_FlagInterval");
-							case "retries":
-								return this.markdown.getMarkdown("HEALTHCHECK_FlagRetries");
-							case "start-period":
-								return this.markdown.getMarkdown("HEALTHCHECK_FlagStartPeriod");
-							case "timeout":
-								return this.markdown.getMarkdown("HEALTHCHECK_FlagTimeout");
+			switch (instruction.getKeyword()) {
+				case "HEALTHCHECK":
+					let flags = (instruction as ModifiableInstruction).getFlags();
+					for (let flag of flags) {
+						if (Util.isInsideRange(textDocumentPosition.position, flag.getNameRange())) {
+							switch (flag.getName()) {
+								case "interval":
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagInterval");
+								case "retries":
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagRetries");
+								case "start-period":
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagStartPeriod");
+								case "timeout":
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagTimeout");
+							}
+							return null;
 						}
-						return null;
 					}
-				}
+					break;
+				case "ONBUILD":
+					if ((instruction as Onbuild).getTriggerInstruction() === "HEALTHCHECK") {
+						for (let arg of instruction.getArguments()) {
+							let value = arg.getValue().toUpperCase();
+							if ((value === "CMD" || value === "NONE") && arg.isBefore(textDocumentPosition.position)) {
+								return null;
+							}
+						}
+
+						for (let arg of instruction.getArguments()) {
+							if (Util.isInsideRange(textDocumentPosition.position, arg.getRange())) {
+								let value = arg.getValue();
+								if (value.indexOf("--interval") === 0) {
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagInterval");
+								}
+								if (value.indexOf("--retries") === 0) {
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagRetries");
+								}
+								if (value.indexOf("--start-period") === 0) {
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagStartPeriod");
+								}
+								if (value.indexOf("--timeout") === 0) {
+									return this.markdown.getMarkdown("HEALTHCHECK_FlagTimeout");
+								}
+							}
+						}
+					}
+					break;
+
 			}
 		}
 
diff --git a/test/dockerHover.test.ts b/test/dockerHover.test.ts
index 0867cfe..346d73e 100644
--- a/test/dockerHover.test.ts
+++ b/test/dockerHover.test.ts
@@ -731,59 +731,70 @@ describe("Dockerfile hover", function() {
 			});
 		});
 
-		describe("HEALTHCHECK", function() {
-			it("--interval", function() {
-				let document = createDocument("HEALTHCHECK --interval");
-				let hover = onHover(document, 0, 17);
-				assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagInterval"));
-			});
+		function createHealthcheckTest(trigger: boolean) {
+			let onbuild = trigger ? "ONBUILD " : "";
+			let triggerOffset = onbuild.length;
+
+			describe("HEALTHCHECK", function() {
+				it("--interval", function() {
+					let document = createDocument(onbuild + "HEALTHCHECK --interval");
+					let hover = onHover(document, 0, triggerOffset + 17);
+					assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagInterval"));
+				});
 
-			it("--interval=\\$x", function() {
-				let document = createDocument("HEALTHCHECK --interval=\\$x");
-				let hover = onHover(document, 0, 17);
-				assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagInterval"));
-			});
+				it("--interval=\\$x", function() {
+					let document = createDocument(onbuild + "HEALTHCHECK --interval=\\$x");
+					let hover = onHover(document, 0, triggerOffset + 17);
+					assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagInterval"));
+				});
 
-			it("--interval=\\a", function() {
-				let document = createDocument("HEALTHCHECK --interval=\\a");
-				let hover = onHover(document, 0, 17);
-				assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagInterval"));
-			});
+				it("--interval=\\a", function() {
+					let document = createDocument(onbuild + "HEALTHCHECK --interval=\\a");
+					let hover = onHover(document, 0, triggerOffset + 17);
+					assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagInterval"));
+				});
 
-			it("--retries", function() {
-				let document = createDocument("HEALTHCHECK --retries");
-				let hover = onHover(document, 0, 17);
-				assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagRetries"));
-			});
+				it("--retries", function() {
+					let document = createDocument(onbuild + "HEALTHCHECK --retries");
+					let hover = onHover(document, 0, triggerOffset + 17);
+					assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagRetries"));
+				});
 
-			it("--start-period", function() {
-				let document = createDocument("HEALTHCHECK --start-period");
-				let hover = onHover(document, 0, 17);
-				assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagStartPeriod"));
-			});
+				it("--start-period", function() {
+					let document = createDocument(onbuild + "HEALTHCHECK --start-period");
+					let hover = onHover(document, 0, triggerOffset + 17);
+					assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagStartPeriod"));
+				});
 
-			it("--timeout", function() {
-				let document = createDocument("HEALTHCHECK --timeout");
-				let hover = onHover(document, 0, 17);
-				assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagTimeout"));
+				it("--timeout", function() {
+					let document = createDocument(onbuild + "HEALTHCHECK --timeout");
+					let hover = onHover(document, 0, triggerOffset + 17);
+					assert.equal(hover,  markdownDocumentation.getMarkdown("HEALTHCHECK_FlagTimeout"));
+				});
+
+				function createFlagsAfterTest(subcommand: string) {
+					it("flags after " + subcommand, function() {
+						let document = createDocument(onbuild + "HEALTHCHECK " + subcommand + " \\\n--interval=30s\\\n--retries=3\\\n--start-period=30s\\\n--timeout=30s");
+						let hover = onHover(document, 1, 4);
+						assert.equal(hover,  null);
+						hover = onHover(document, 2, 4);
+						assert.equal(hover,  null);
+						hover = onHover(document, 3, 4);
+						assert.equal(hover,  null);
+						hover = onHover(document, 4, 4);
+						assert.equal(hover,  null);
+					});
+				}
+
+				createFlagsAfterTest("CMD");
+				createFlagsAfterTest("NONE");
 			});
+		}
+
+		createHealthcheckTest(false);
 
-			function createFlagsAfterTest(subcommand: string) {
-				it("flags after " + subcommand, function() {
-					let document = createDocument("HEALTHCHECK " + subcommand + " \\\n--interval=30s\\\n--retries=3\\\n--start-period=30s\\\n--timeout=30s");
-					let hover = onHover(document, 1, 4);
-					assert.equal(hover,  null);
-					hover = onHover(document, 2, 4);
-					assert.equal(hover,  null);
-					hover = onHover(document, 3, 4);
-					assert.equal(hover,  null);
-					hover = onHover(document, 4, 4);
-					assert.equal(hover,  null);
-				});
-			}
-
-			createFlagsAfterTest("CMD");
-			createFlagsAfterTest("NONE");
+		describe("ONBUILD", function() {
+			createHealthcheckTest(true);
 		});
 	});